# tutor4physics.com ## Posts - [Unlock the Secrets of Physics with Tutor4Physics](https://tutor4physics.com/unlock-the-secrets-of-physics-with-tutor4physics/): Physics is everywhere—whether it’s the sparkle of a diamond, the color of the sky, or the way a ball curves in motion. Yet for many students, physics often feels overwhelming: endless formulas, confusing concepts, and exam pressure. That’s where [Your Website Name] comes in. We’ve built a learning space designed to make physics not just understandable, but enjoyable. Our goal is simple: help students master physics with clarity and confidence. What Makes Us Different? Instead of rote memorization, we focus on understanding and application. Each concept is explained step by step, backed with solved examples, real-life applications, and question banks […] ## Pages - [Home](https://tutor4physics.com/): Master Physics with Clarity and Confidence at Tutor4Physics—your one-stop platform for making physics simple, logical, and exam-ready. From motion, mechanics, electricity, magnetism, gravitation, optics, thermal physics, to work, power, and energy, we cover the entire curriculum with step-by-step solved examples, question banks, assignments, formula sheets, and real-life applications that bring concepts to life. Whether you want to score high in school exams, crack competitive tests, or strengthen your fundamentals, Tutor4Physics helps you stop memorizing and start understanding. Curious about everyday phenomena like why the sky is blue, why fog lights are yellow, or why diamonds sparkle? We’ve got you covered. […] - [Examination Tips](https://tutor4physics.com/examination-tips/): 1. Use your revision time effectively. Prepare a revision time table. 2. When is your energy level the highest. This is the time to tackle the difficult bits. 3. Do not postpone the difficult topics. 4. Attend to routine things like tidying up, at low energy times of the day. 5. Do not just read. Make notes. In fact summarizing and condensing notes focuses your mind. 6. Discuss topics, after having revised them, with your classmates. 7. Use diagrammatic representation where ever possible. You may find this easier to retain. 8. Take a 5 minutes break after every 40 minutes […] - [Work Energy Power](https://tutor4physics.com/work-energy-power/): Imagine a porter carrying a load on his head. Is he doing any work? Yes, one would say! He would be paid for carrying that load from one place to another. But in terms of Physics he is not doing any work! Again, imagine a man pushing a wall? Do you think he is doing any work? Well, his muscles are contracting and expanding. He may even be sweating. But in Physics, we would say he is not doing any work!   If the porter is carrying a very heavy load for a long distance, we would say he has […] - [Work Done](https://tutor4physics.com/work-done/):  Consider the simplest possible case of work done. A force F is acting on an object. The object has a displacement S in the direction of the force. Then the work done is the product of force and displacement.     What will happen in the case when the applied force is not in the direction of displacement but rather at an angle to it. In such a case we will consider the component of force in the direction of displacement. This component will be effective in doing work as shown. Component of force in the direction of displacement is […] - [Why is the sun reddish during sunrise and sunset?](https://tutor4physics.com/why-is-the-sun-reddish-during-sunrise-and-sunset/): During sunrise or sunset, the sun is near the horizon. The sun’s light has to travel the longest distance through the atmosphere. As it travels most of the colors are scattered away according to Rayleigh’s criterion According to the Rayleigh’s criterion, the intensity of scattered light is inversely proportional to the fourth power of the wavelength if the size of the scatterers are of the order of the wavelength of light. Air molecules have their size of this order. Red reaches our eyes since it has the longest wavelength. - [Why is the sky blue?](https://tutor4physics.com/why-is-the-sky-blue/): Sunlight contains visible and invisible parts or electromagnetic spectrum. The visible colors of light are violet, indigo, blue, green, yellow, orange, red (VIBGYOR). According to the Rayleigh’s criterion, the intensity of scattered light is inversely proportional to the fourth power of the wavelength if the size of the scatterers are of the order of the wavelength of light. Air molecules have their size of this order. Thus shorter wavelength of blue (450 nm) is scattered much more than the longer wavelength of red (700nm). Thus the sky looks blue Violet color has even shorter wavelength (330nm) but the sky does […] - [Why is the grass green?](https://tutor4physics.com/why-is-the-grass-green/): We are able to see objects because of the light reflected from them is perceived by our eyes. Objects absorb certain wavelengths and reflect the other. It is the color of the reflected wavelengths which imparts color to the objects. Now, grass absorbs the other colors of light and reflects green light. This green light reaches our eyes when we look at grass. Thus grass is green. wi What will be the color of glass if we look at it through a green filter? Since the green filter will block out green light, no color will reach our eyes and […] - [Why do diamonds sparkle?](https://tutor4physics.com/why-do-diamonds-sparkle/): When light goes from one medium to another, it bends. This phenomenon is called refraction. When it goes from rarer to denser it bends towards the normal. When it goes from denser to rarer, it bends away from the normal. Let us consider light coming from denser to rarer medium (air). i is the angle of incidence and r is the angle of refraction in the rarer medium. As we increase i r also increases. For a certain angle i, angle of refraction r in the rarer medium becomes 90o. This particular angle i is called the critical angle c. […] - [Why are the oceans blue?](https://tutor4physics.com/why-are-the-oceans-blue/): Pure water, because of the nature of oxygen-hydrogen bonds in the water molecules, absorbs more of the longer wavelengths of the visible spectrum of the light which is the wavelength of red light. On the other hand water absorbs much lesser of the shorter wavelength of light which is the wavelength of blue light. This effect becomes visible in large quantities of water as a lake or ocean. Water in a water glass or a bucket of water is much lesser so this effect is not seen. As we dive underwater light becomes dimmer and dimmer and also bluish. Different […] - [Why are the fog lights yellow?](https://tutor4physics.com/why-are-the-fog-lights-yellow/): According to the Rayleigh’s criterion, the intensity of scattered light is inversely proportional to the fourth power of the wavelength if the size of the scatterers are of the order of the wavelength of light. However, this criterion is not applicable fog, rain and snow. The size of the scattering particles in these situations are much larger thatn the wavelength of visible light. So the scattering or penetration of all the colors will be the same. However, the blue and violet wavelengths are difficult for the human visual system to process. Also blue-violet range caries more glare. Thus fog light […] - [Why are clouds white?](https://tutor4physics.com/why-are-clouds-white/): Clouds are made of water vapours which are much larger than the air molecules. so Rayleigh’s criterion does not apply According to the Rayleigh’s criterion, the intensity of scattered light is inversely proportional to the fourth power of the wavelength if the size of the scatterers are of the order of the wavelength of light. Air molecules have their size of this order. However, as we have seen water vapours are much larger than air molecules and all colors of light are scattered equally. Thus all colors of light combine to make white light. - [Why are the rain clouds dark?](https://tutor4physics.com/why-are-the-rain-clouds-dark/): Usually the clouds are white as they scatter all colors of light equally. However, the rain clouds are very dense. They block most of the sunlight. Thus they appear dark - [Various units of energy](https://tutor4physics.com/various-units-of-energy/): There are five different units to express energy: J or Joule It is the SI unit. ergs It is the cgs unit. calorie or cal It is usually used for heat or thermal energy. kWhr It is used for electrical energy. It is also called the commercial unit of electrical energy. eV It is normally used in modern physics. Relation between various units of energy: 1 J = 107 ergs i cal = 4.186 J 1 kWhr = 3.6 x 10 6 J 1 eV = 1.6 x 10 -19 J - [Work with Variable Force](https://tutor4physics.com/work-with-variable-force/): Force in everyday life is usually not a constant force. So far, when we have discussed work done, we have assumed that the force is constant. What happens if the force is variable? The figure below is a graph of varying force in one dimension.   Let us first understand how do we find work done from a graph. If we are talking about a constant force, the area under the graph (which will be a rectangle) gives us the work done. - [Units of Work](https://tutor4physics.com/units-of-work/): Since work done W = F.S, its units are force times length. The SI unit of work is Newton-meter (Nm). Another name for it is Joule (J).  1 Nm = 1 J  The unit of  work in cgs system is dyne cm or erg  Note that 1 J = 107 ergs.  The dimensional formula of work is [ML2T-2] System Unit of work Name of the combined unit SI Newton meter (Nm) Joule cgs Dyne centimeter (dyne-cm) Erg - [Third Law of Motion](https://tutor4physics.com/third-law-of-motion/): An example When you try to push a wall, it pushes your right back! The harder you push the more force is felt by your hands. This is what Newton’s third law of motion deals with. Third law of motion If a body exerts a force on another, there is an equal and opposite force, called a reaction on the first body by the second. Do the force and its reaction cancel each other? No, as they are acting on different bodies. For equal and opposite forces to cancel, they must act on the same body. In the case of […] - [Second Law of Motion](https://tutor4physics.com/second-law-of-motion/): The rate of change of momentum of a moving body is proportional to and is in the same direction as the force acting on it F = d(mv)/dt where F is the applied force, v is the velocity of the body, and m its mass. If mass remains constant F = mdv/dt or F =ma where a is the acceleration The direction of acceleration is the same as that of F. As F = ma it follows that for a fixed mass, greater the force, greater the acceleration. The SI unit of force is Newton. 1 Newton is equal to […] - [First law of motion](https://tutor4physics.com/first-law-of-motion/): Why does an object move? What are the laws that make it move the way it does? Sir Isaac Newton (1642 – 1721) answered these questions. First law of motion A body continues in a state of rest or uniform motion in a straight line unless, it is acted upon by external forces. Push a ball along the floor. It moves but comes to rest after some time, even when there is no apparent external force acting on it. But then there is an external force. This force is friction. If we remove friction the ball will not stop, unless […] - [Capacitor with Dielectric](https://tutor4physics.com/capacitor-with-dielectric/): What is a dielectric A dielectric material is an insulator in which there are no free electrons. This means that a dielectric will not be able to conduct current. Dielectric constant Dielectric constant K can be written as a ratio of Permittivity of the medium to Permittivity of free space. It can also be defined as the ratio of the capacitance with dielectric as the medium and is the capacitance with air or vacuum between the plates. Further it can also be defined as the ratio of the electric field between the plates with air or vacuum as the medium […] - [Conservation of Momentum](https://tutor4physics.com/conservation-of-momentum/): An Example Let us take two bodies say two balls. We assume that these balls are in a place where no external forces are acting on them. Such a place would be called an isolated system. Let one ball be moving along a straight line with velocity v1 and let the other ball be moving with a velocity v2. Now these velocities are different. So, as both balls are moving along the same line, they will hit each other at some point of time if the ball, which is following is moving at a faster speed. If you were to […] - [Principle of a Capacitor](https://tutor4physics.com/principle-of-a-capacitor/): What is a Capacitor It is a device used to store charge in an electrical circuit An every day use To remove sparking in the ignition system of an automobile. When an electric current is switched on or off there is an induced current which can create sparking. If we put a capacitor in the circuit this current charges the capacitor instead and this will avoid occurrence of sparking. Charge is proportional to potential When a charge is given to a conductor its potential rises. If we give a conductor a charge Q then its potential rises. The greater the […] - [Ray optics formulas](https://tutor4physics.com/ray-optics-formulas/): Refraction The phenomenon of change in the path of light when it passes from one medium to another Laws of refraction First The incident ray, the refracted ray and the normal at the point of incidence all lie in the same plane Second Sin i / Sin r = μ [refractive index of the second medium with respect to the first medium] Also μ = c/v or v1/v2 μ = Real depth / Apparent depth Light enters medium a, crosses medium b and then leaves from medium c, then aμc = aμb x bμc Total internal reflection When light travelling […] - [Projectile Motion](https://tutor4physics.com/projectile-motion/): Projectile Projectile is a body thrown with an initial velocity in the vertical plane and then it moves in two dimensions under the action of gravity alone without being propelled by any engine or fuel. Its motion is called projectile motion. The path of a projectile is called its trajectory. Examples: A packet released from an airplane in flight. A golf ball in flight. A bullet fired from a rifle. A jet of water from a hole near the bottom of a water tank. Projectile motion is a case of two-dimensional motion .Any case of two dimensional motion can be […] - [Positive and Negative Work](https://tutor4physics.com/positive-and-negative-work/):  We have seen the situations when the work done is zero. Work done can also be positive or negative. When 0o <= θ < 90o, work done is positive as  Cos θ is positive. Work done by a force is positive if the applied force has a component in the direction of the displacement. When a body is falling down, the force of gravitation is acting in the downward direction. The displacement is also in the downward direction. Thus the work done by the gravitational force on the body is positive. Consider the same body being lifted in the upward […] - [Parallelogram law of vector addition Questions and Answers](https://tutor4physics.com/parallelogram-law-of-vector-addition-questions-and-answers/): Note: vectors are shown in bold. scalars are shown in normal type The diagram above shows two vectors A and B with angle p between them. R is the resultant of A and B R = A + B This is the resultant in vector R is the magnitude of vector R Similarly A and B are the magnitudes of vectors A and B R = √(A2 + B2 2ABCos p) or [A2 + B2 2ABCos p]1/2 To give the direction of R we find the angle q that R makes with B Tan q = (A Sin p)/(B + […] - [Circular Motion](https://tutor4physics.com/circular-motion/): Velocity is a vector quantity. Its magnitude is called speed and also it has a direction. A body of mass m is moving in a circular path of radius r. There are two possibilities: First possibility If the speed is constant, the motion is called uniform circular motion. Speed is constant but the direction is changing continuously, so the motion is accelerated. And the acceleration is along the radius towards the center. This acceleration is called centripetal acceleration or even radial acceleration and is given by the relation: a = v2 / r Where v is the speed. The direction […] - [Scalars and Vectors](https://tutor4physics.com/scalars-and-vectors/): Scalar or vector? To explain the difference we use two words: ‘magnitude’ and ‘direction’. By magnitude we mean how much of the quantity is there. By direction we mean is this quantity having a direction which defines it. Physical quantities which are completely specified by just giving out there magnitude are known as scalars. Examples of scalar quantities are distance, mass, speed, volume, density and temperature. Other physical quantities cannot be defined by just their magnitude. To define them completely we must also specify their direction. Examples of these are velocity, displacement, acceleration, force, torque and momentum. These are called […] - [Density and Pressure](https://tutor4physics.com/density-and-pressure/): Density The mass of a substance contained in unit volume is its density D. D = m/V Measuring of densities of substances is easier if we compare them with the density of some other substance of know density. Water is used for this purpose. The ratio of the density of the substance to that of water is called the Specific Gravity SG of the substance. SG = Dsubstance / Dwater The density of water is 1000 kg/m3 - [Work, Power, Energy Questions and Answers](https://tutor4physics.com/work-power-energy-questions-and-answers/): A person pushes a 10 kg cart a distance of 20 meters by exerting a 60 Newton horizontal force. The frictional resistance force is 50 Newtons. How much work is done by each force acting ont he cart? How much kinetic energy does the cart have at the end of the 20 meters if it started from rest: Mass of cart = 10 kg Distance moved = 20 m Horizontal force = 60 N Frictional force = 60 N Frictional resistance force = 50 N Net force = 60 – 50 = 10 N Work done by the horizontal force […] - [Answers to Properties of Matter Questions](https://tutor4physics.com/answers-to-properties-of-matter-questions/): Q.    A volume of 8 liters of gas has a pressure of 50 kPa and a temp of 27oC. a)    If the pressure were increased to 300 kPa without changing he temperature what would be the resulting volume? V1 = 8 liters P1 = 50 kPa T1 = 27o C = 300 K If the temperature is constant, then pressure is inversely proportional to the volume ( Boyle’s Law) that is P a 1/V or PV = constant P1V1 = P2V2 P2 = 300 kPa 50 x 103 x 8 = 300 x 103 x V2 V2 = (50 x […] - [Electricity Questions and Answers](https://tutor4physics.com/electricity-questions-and-answers/): In a region where there is an electric field, the electric forces do +8.0 x 10-19 J of work on an electron as it moves from point X to point Y. Which point, X or Y is at a higher potential? What is the potential difference, Vy – Vx , between point Y and point X? W = qV If W is positive, either both q and V are positive or both q and V are negative. Since electron ha a negative charge, V should be negative in this case (W is positive). Thus final potential must be less than […] - [Answers to Two and Three Dimension of motion Questions](https://tutor4physics.com/answers-to-two-and-three-dimension-of-motion-questions/): Q A billiard ball (A) with a mass of 0.165 kg is traveling at 4.2 m/s. It strikes ball B, which is identical to ball A and is stationary. Ball moves on at angle of 25 degrees to the left of its original direction, which ball B moves 65 degrees to the right. a) Draw a vector diagram to show how the law of conservation of momentum could be applied to this situation. b) Write a simplified equation, in terms of mass and the velocity variables, to show how the law of conservation of momentum could be applied to this […] - [Impulse](https://tutor4physics.com/impulse/): This is the change in the momentum of a body caused over a very short time. Let m be the mass and v and u the final and initial velocities of a body. Impulse = Ft = mv – mu - [Glossary of Physics Terms](https://tutor4physics.com/glossary-of-physics-terms/): Absolute humidity (or Saturation value) The maximum amount of water vapor, which could be present in 1 m³ of the air at any given temperature, is called absolute humidity. Absolute magnitude A classification scheme, which compensates for the distance, differences to stars. It calculates the brightness that stars would appear to have if they were all at a defined, standard distance of 10 parsec Absolute scale Temperature scale set so that zero is at the theoretical lowest temperature possible. This would occur when all random motion of molecules has ceased Absolute zero The theoretical lowest temperature possible, which occurs when […] - [Formula: Newton's Law of Universal Gravitation](https://tutor4physics.com/formula-newtons-law-of-universal-gravitation/): About fifty years after Kepler announced the laws now named after him, Isaac Newton showed that every particle in the Universe attracts every other with a force which is proportional to the products of their masses and inversely proportional to the square of their separation. Hence: If F is the force due to gravity, g the acceleration due to gravity, G the Universal Gravitational Constant (6.67×10-11 N.m2/kg2), m the mass and r the distance between two objects. Then F = G m1 m2 / r2 - [Formulas for work and energy](https://tutor4physics.com/formulas-for-work-and-energy/): As we know from the law of conservation of energy: energy is always conserved. Work is the product of force and the distance over which it moves. Imagine you are pushing a heavy box across the room. The further you move the more work you do! If W is work, F the force and x the distance then. W = Fx Energy comes in many shapes. The ones we see over here are kinetic energy (KE) and potential energy (PE) Transitional KE = ½ mv2 Rotational KE = ½ Iw2 here I is the moment of inertia of the object […] - [Formulas for power](https://tutor4physics.com/formulas-for-power/): Power (P) is work( W) done in unit time (t). P = W/t as work and energy (E) are same it follows power is also energy consumed or generated per unit time. P = E/t In measuring power Horsepower is a unit which is in common use. However in physics we use Watt. So the first thing to do in solving any problem related to power is to convert horsepower to Watts. 1 horsepower (hp) = 746 Watts - [Formulas Motion in One Dimension with Solved Examples](https://tutor4physics.com/formulas-motion-in-one-dimension-with-solved-examples/): By one dimension we mean that the body is moving only in one plane and in a straight line. Like if we roll a marble on a flat table, and if we roll it in a straight line (not easy!), then it would be undergoing one-dimensional motion. There are four variables which put together in an equation can describe this motion. These are Initial Velocity (u); Final Velocity (v), Acceleration (a), Distance Traveled (s) and Time elapsed (t). The equations which tell us the relationship between these variables are as given below. v = u + at v2 = u2 […] - [Formulas for Kepler's Laws](https://tutor4physics.com/formulas-for-keplers-laws/): Towards the end of the sixteenth century, Tycho Brahe collected a huge amount of data giving precise measurements of the position of planets. Johannes Kepler, after a detailed analysis of the measurements announced three laws in 1619. 1.  The orbit of each planet is an ellipse which has the Sun at one of its foci. 2.  Each planet moves in such a way that the (imaginary) line joining it to the Sun sweeps out equal areas in equal times. 3.  The squares of the periods of revolution of the planets about the Sun are proportional to the cubes of their […] - [Formula for Resistance of Resistors in Series](https://tutor4physics.com/formula-for-resistance-of-resistors-in-series/): < The equivalent resistance (Req) of a set of  resistors connected in series is Req = R1 + R2 + R3 + – – – - [Formula Newton's Second Law](https://tutor4physics.com/formula-newtons-second-law/): The acceleration of a body is directly proportional to the net unbalanced force and inversely proportional to the body’s mass, a relationship is established betweenForce (F), Mass (m) and acceleration (a). This is of course a wonderful relation and of immense usefulness. F = m x a   - [Physics Formulas](https://tutor4physics.com/physics-formulas/): One Dimensional Motion Time and Distance By one dimension we mean that the body is moving only in one plane and in a straight line. Like if we roll a marble on a flat table, and if we roll it in a straight line (not easy!), then it would be undergoing one-dimensional motion. There are four variables which put together in an equation can describe this motion. These are Initial Velocity (u); Final Velocity (v), Acceleration (a), Distance Traveled (s) and Time elapsed (t). The equations which tell us the relationship between these variables are as given below. v = […] - [Formula for Pressure](https://tutor4physics.com/formula-for-pressure/): Pressure (P) is Force (F) per unit area (A) P = F/A   - [Formula Resistance of Resistors in Parallel](https://tutor4physics.com/formula-resistance-of-resistors-in-parallel/): The equivalent resistance (Req) of a set of resistors connected in parallel is 1/Req = 1/R1 + 1/R2 + 1/R3 + – – – - [Formula for Ohm's Law](https://tutor4physics.com/formula-for-ohms-law/): According to Ohm’s Law electric potential difference(V) is directly proportional to the product of the current(I) times the resistance(R). V = I R The relationship between power (P) and current and voltage is P = I V Using the equations above we can also write P = V2 / R and P = I2 R - [Formula for Momentum](https://tutor4physics.com/formula-for-momentum/): Momentum (p) is the quantity of motion in a body. A heavy body moving at a fast velocity is difficult to stop. A light body at a slow speed, on the other hand can be stopped easily. So momentum has to do with both mass and velocity. p = mv - [Formula: Acceleration due to gravity outside the Earth](https://tutor4physics.com/formula-acceleration-due-to-gravity-outside-the-earth/): It can be shown that the acceleration due to gravity outside of a spherical shell of uniform density is the same as it would be if the entire mass of the shell were to be concentrated at its center. Using this we can express the acceleration due to gravity (g’) at a radius (r) outside the earth in terms of the Earth’s radius (re) and the acceleration due to gravity at the Earth’s surface (g) g’ = (re2 / r2) g - [Formula: Acceleration due to gravity inside the Earth](https://tutor4physics.com/formula-acceleration-due-to-gravity-inside-the-earth/): Here let r represent the radius of the point inside the earth. The formula for finding out the acceleration due to gravity at this point becomes: g’ = ( r / re )g In both the above formulas, as expected, g’ becomes equal to g when r = re. - [Formula for Density](https://tutor4physics.com/formula-for-density/): The mass of a substance contained in unit volume is its density (D). D = m/V Measuring of densities of substances is easier if we compare them with the density of some other substance of know density. Water is used for this purpose. The ratio of the density of the substance to that of water is called the Specific Gravity (SG) of the substance. SG = Dsubstance / Dwater The density of water is 1000 kg/m3 - [Formula Circular Motion](https://tutor4physics.com/formula-circular-motion/): In the diagram v is the tangential velocity of the object. a is the centripetal (acting towards the center of the circle) acceleration and F is the centripetal force. r is the radius of the circle and m is mass of the object. a = v2 / r F = ma = mv2/r - [Examples on Work Done](https://tutor4physics.com/examples-on-work-done/): Examples on Work Done Example 1 A box is dragged horizontally across a floor by a 100 N force acting parallel to the floor. What is the work done by the force in moving it through a distance of 8 m F = 100 N S = 8 m Since F and S are in the same direction, θ = 0, where θ is the angle of the force to the direction of movement. W = F Cos θ = 100 x 8 x Cos 0 = 800 J (Cos 0 = 1) Example 2 A box is dragged across […] - [Example work done by variable force](https://tutor4physics.com/example-work-done-by-variable-force/): A force F = 2x + 5 acts on a particle. Find the work done by the force during the displacement of the particle from x =0m to x = 2m. Given that the force is in Newtons. Work done W = ∫F(x)dx Thus W = = ∫F(x)dx Cos 0o = ∫F(x)dx = ∫(2x + 5)dx = 2x2/2 + 5x | = 22 + 5 x 2 = 14 J - [How to solve a Physics question](https://tutor4physics.com/how-to-solve-a-physics-question/): Step 1 Read Problem A bullet is fired from a rifle with a horizontal velocity of 500 feet per second from a height of 16feet at the same time, another bullet falls out of the gun. without obstruction, which bullet will reach the ground first? how long will it take? At what velocity will it hit? Step 2 Draw Diagram Step 3 Identify Data We will take the downward direction of motion as positive.  In the case of Bullet A  uah = Horizontal component of initial velocity ua  uav = Vertical component of initial velocity ua  It is convenient to […] - [Electrostatics formulas](https://tutor4physics.com/electrostatics-formulas/): Electrostatic force Coulomb’s Law F = kq1q2/r2 where k=1/4πεo=9×109Nm2C-2 εo = 8.85×10-12C2m-2N-1 See a solved example at Buzztutor.com Vector notation Electrostatic field Electric field due to a point charge E = F/qo = kq/r2 N/C See a solved example at Buzztutor.com E due to circular loop of charge (radius r) at a distance x from the center Electric dipole Dipole moment Cm Electric field at an axial point of a dipole Electric field at an equatorial point of a dipole Torque acting on a dipole in a uniform electric field Potential energy of a dipole in a uniform electric field […] - [Electricity: Ohm's Law](https://tutor4physics.com/electricity-ohms-law/): According to Ohm’s Law electric potential difference(V is directly proportional to the product of the current(I times the resistance(R. V = I R The relationship between power (P and current and voltage is P = I V Using the equations above we can also write P = V2 / R and P = I2 R - [Cases where work is not done](https://tutor4physics.com/cases-where-work-is-not-done/): Let us consider some cases where work is not done: Work is zero if applied force is zero (W=0 if F=0): If a block is moving on a smooth horizontal surface (frictionless), no work will be done. Note that the block may have large displacement but no work gets done. Work is zero if Cos θ is zero or θ = Π/2. this explains why no work is done by the porter in carrying the load. As the porter carries the load by lifting it upwards and the moving forward it is obvious the angle between the force applied by […] - [Assignment on Gauss's Theorem](https://tutor4physics.com/assignment-on-gauss-s-theorem/): Question 1 A point charge of +2μC is kept at a distance of 6cm above the center of a square of side 12cm. Find the flux through the square. Ans: 3.76 x 105 Nm2C-1 Question 2 The electric flux through the spherical Gaussian surface of 5.0 cm radius is -1.0 x 103Nm2C-1 (a) What is the charge inside the spherical surface? (b) If the radius of the Gaussian surface is doubled, how much flux would pass through the surface. (c) If the net outward flux is zero, can we conclude that there are no charges inside the surface? Explain. Ans: […] - [Assignment on electric potential and potential energy](https://tutor4physics.com/assignment-on-electric-potential-and-potential-energy/): A charge of 2C is taken from a point where the potential is -20V to point where the potential is V. If 400 J of work is done in the process, find V. Ans: 180V Question 2 Toe point charges of -10μC and +40μC are kept 15 cm apart. At which point on the line joining them will the electric potential be zero. Ans: 3 cm from -10μC charge Question 3 Three point charges Q1=25μC, Q2=50μC Q3=100μC are kept at the corners A, B and C respectively of an equilateral triangle ABC having each side of 7.5 m. find the […] - [Assignment on charge, electric force, electric field and dipole](https://tutor4physics.com/assignment-on-charge-electric-force-electric-field-and-dipole/): Question 1 A charged oil drop has a mass 2.2×10-15kg. It remains suspended in an electric field of intensity 4.5×104 NC-1. What is the charge on the drop. What will be the nature of the charge and is it possible for the drop to have this charge? Ans: 4.8×10-19C, +ve charge, n=3, Yes Question 2 Two point charges +2×10-8 C and -2×10-8 C are placed 6 cm apart. A charge of +1×10-8 C is placed such that it is 5 cm away from each charge. Find the force acting on the third charge. Ans: 8.64 x 10-4N Question 3 Two […] - [2 and 3 Dimension Motion Q and A](https://tutor4physics.com/2-and-3-dimension-motion-q-and-a/): Question 1 A billiard ball (A) with a mass of 0.165 kg is traveling at 4.2 m/s. It strikes ball B, which is identical to ball A and is stationary. Ball moves on at angle of 25 degrees to the left of its original direction, which ball B moves 65 degrees to the right. a) Draw a vector diagram to show how the law of conservation of momentum could be applied to this situation. b) Write a simplified equation, in terms of mass and the velocity variables, to show how the law of conservation of momentum could be applied to […] - [Temperature Q and A](https://tutor4physics.com/temperature-q-and-a/): Moment of Inertia Temperature Elasticity Question 1 A volume of 8 liters of gas has a pressure of 50 kPa and a temp of 27oC. a)    If the pressure were increased to 300 kPa without changing he temperature what would be the resulting volume?b)    If the temperature was raised to 627o C while maintaining the original pressure, what would be the final volume?c)     What would be the resulting volume if the temperature was raised to 627oC and the pressure increased to 300 kPa simultaneously? Click here to See Hint Hint 1 If the temperature is constant, then pressure is inversely […] - [One Dimension Motion Q and A](https://tutor4physics.com/one-dimension-motion-q-and-a/): Question 1 Suppose an object undergoes a change in velocity from +1m/s to 4m/s. Is its velocity becoming more positive or less positive than it was before? What direction (s) is the object moving? Is the acceleration positive or negative? Explain your response. Are the velocity and acceleration in the same direction during the time interval of the change in velocity? Explain. Click here to See Hint Hint 1 Find out whether difference between the initial and final velociyt is positive or negative. Us the formula V-U+at to determine whether the acceleration is positive or negative. Click here to See […] - [Laws of Motion Q and A](https://tutor4physics.com/laws-of-motion-q-and-a/): Question 1 A120 lb person is being lifted aloft by a rocket which accelerates uniformly to an upward speed of 300 ft/sec in 2 sec. What is the upward acceleration in multiples of g? Click here to See Hint Hint 1 Acceleration of the rocket can be calculated from first equation of motion v = u + at Click here to See Answer Answer 1 Mass of the man = 120lb Final speed of the rocket = 300 ft/sec Time = 2 sec Acceleration of the rocket can be calculated from first equation of motion v = u + at […] - [Gravitation Moment of Inertia Q and A](https://tutor4physics.com/gravitation-moment-of-inertia-q-and-a/): Question 1 The earth moves about the sun in an elliptical orbit. As the earth moves closer to the sun, which of the following best describes the earth-sun system’s moment of inertia? a.       it is zero b.      it decreases c.       it increases d.      it remains constant e.       none of the above choices are valid Click here to See Hint Hint 1 Moment of inertia I = Sqmi ri2 Click here to See Answer Answer 1 Moment of inertia I = Sqmi ri2 As the earth moves closer to the sun, r decreases, but, mass of the system is constant. - [Gravitation Force Q and A](https://tutor4physics.com/gravitation-force-q-and-a/): Question A sphere shell has inner radius R, outer radius R, and mass M, distributed uniformly throughout the shell. Find the magnitude of the gravitational force exerted on the shell by a point particle of mass m located at a distance d from the center, outside the inner radius and inside the outer radius. Paragraph Click here to See Hint Hint The mass of the spherical shell that will cause force will be mass located between the spheres of radius d and radius R1. As mass is distributed uniformly in the shell we can determine the density. Then we can […] - [Elasticity Q and A](https://tutor4physics.com/elasticity-q-and-a/): Question 1 A cord is 5.71e+1 meters long and 1.56 mm in diameter. When it supports a 1.41 kg load it stretches 3.50 cm. What is the Young’s modulus of the cord’s material? Click here to See Hint Hint 1 Young’s modulus Y = (F/A)/(Δl/l) = stress / strain = F l /A Δl where F=mg Click here to See Answer Answer 1 length l = 5.71 x 10 m = 57.1 m d = 1.56 mm = 1.56 x 10-3 m r = 0.78 x 10-3m m = 1.41 kg Increase in length Δl = 3.5 x 10-2 m […] - [Circular Motion Q and A](https://tutor4physics.com/circular-motion-q-and-a/): Question 1 A constant torque of 1.56 N-m is applied to a rotating solid disk of radius 15 cm and mass 5.71 kg. What is the angular velocity of the disk after 10 seconds? Click here to See Hint Hint 1 Initial angular velocity w0 of the disc is not given. We assume it to be zero. Final angular velocity of the disc = w = w0 + at where a is the angular acceleration and torque T = I a Click here to See Answer Answer 1 Torque T = 1.56 Nm Radius r = 15 cm = 0.15 […] - [Answers](https://tutor4physics.com/answers-3/): Atoms Q. How do we know atoms exist if we can’t see them? A. Even the smallest speck which can be seen through an ordinary microscope contains billions of atoms. However, scientists use very powerful instruments and techniques to study atoms. When X rays are passed through a crystal, the atoms in the crystal diffracts the X-rays in a certain way. These diffracted rays produce patterns on photographic film. In this way scientists are able to find out how the atoms are arranged and how far apart they are. Extremely powerful Scanning Electron Microscopes allow scientists to observe the positions […] - [Physics Questions and Answers](https://tutor4physics.com/physics-questions-and-answers/): Q A singly ionized particle (q = 1.60 x 10-19 C) is moving at 1.9 x 104 m/s and moves perpendicular into a magnetic field of 1.0 x 10-3 T. If the particle moves in a radius of curvature of 0.40 m, determine the mass of the particle. Begin your solution with a statement about forces. Ans radius of curvature r = 0.4 m magnetic field B = 1 x 10-3 T charge = 1.6 x 10-19 C velocity v = 1.9 x 104 m/s A force acts on the charged particle in a magnetic field which is given by […] [comment]: # (Generated by Hostinger Tools Plugin)