# Physics Work Energy And Power Problems And Solutions Pdf

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- Mechanics: Work, Energy and Power
- work and energy problems with solutions pdf

The learning objectives in this section will help your students master the following standards:. Use the lab titled Work and Energy as a supplement to address content in this section. In this section, students learn how work determines changes in kinetic energy and that power is the rate at which work is done.

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Given :. S or mgh. If the coefficient of restitution is 0. The impluse on the ball acts perpendicular to the smooth plane. The component of velocity parallel to the surface will be changed.

According to law of restitution. Squaring and adding 1 and 2. A bob of mass m is attached to one end of the rod of negligible mass and length r, the other end of which is pivoted freely at a fixed center O as shown in the figure. What initial speed must be given to the object to reach the top of the circle?

Hint: Use law of conservation of energy. Is this speed less or greater than speed obtained in the section 4. The horizontal distance, draw the point of projection to the point where the ball returns to the same level. Two different unknown masses A and B collide. A is initially at rest when B has a speed v. Find the direction in which A moves after collision. In x - direction. In y - direction. A bullet of mass 20 g strikes a pendulum of mass 5 kg.

The centre of mass of pendulum rises a vertical distance of 10 cm. If the bullet gets embedded into the pendulum, calculate its initial speed. Pendulum is at rest. From II equation of motion. Substitute the value of v in equation 1. A spring which in initially in un-stretched condition, is first stretched by a length x and again by a further length x.

True or false? Which is conserved in inelastic collision? Total energy or Kinetic energy? Total energy is always conserved. But K. Is there any net work done by external forces on a car moving with a constant speed along a straight road?

If a car is moving at a constant speed, then external force will be zero. So net work done is zero. A car starts from rest and moves on a surface with uniform acceleration. What information you can get from that graph? A charged particle moves towards another charged particle. Under what conditions the total momentum and the total energy of the system conserved?

Find the work done in the process. A body of mass 10kg at rest is subjected to a force of 16N. Find the kinetic energy at the end of 10 s.

A body of mass 5kg is thrown up vertically with a kinetic energy of J. If acceleration due to gravity is 10 ms -2 , find the height at which the kinetic energy becomes half of the original value. Find their velocities after collision. What will be its speed once the force stops? The area under the graph gives the impulse. Hence the particle will reverse its direction and move with its initial speed. The coefficient of restitution between the particle and floor is e. What is the magnitude of v?

Applying component of velocities,. The x - component of velocity is. The magnitude of y — component of velocity is not same, therefore, using coefficient of restitution,. A particle of mass m is fixed to one end of a light spring of force constant k and un-stretched length l. What will be the length increase in the spring? When the spring is rotated in a horizontal circle,. A gun fires 8 bullets per second into a target X. If the mass of each bullet is 3 g and its speed s Then, calculate the power delivered by the bullets.

A box is pulled with a force of 25 N to produce a displacement of 15 m. If the angle between the force and displacement is 30 o , find the work done by the force. Example 4. An object of mass 2 kg falls from a height of 5 m to the ground. What is the work done by the gravitational force on the object? In this case the force acting on the object is downward gravitational force. This is a constant force. Work done by gravitational force is. The object also moves downward which is in the direction of gravitational force as shown in figure.

The work done by the gravitational force on the object is positive. Calculate the work done by gravitational force and normal force on the object. Note that this force is constant throughout the motion of the mass. If an object of mass 2 kg is thrown up from the ground reaches a height of 5 m and falls back to the Earth neglect the air resistance. When the object goes up, the displacement points in the upward direction whereas the gravitational force acting on the object points in downward direction.

The work done by gravitational force in the upward motion. When the object falls back, both the gravitational force and displacement of the object are in the same direction. The total work done by gravity in the entire trip upward and downward motion. It implies that the gravity does not transfer any energy to the object. When the object is thrown upwards, the energy is transferred to the object by the external agency, which means that the object gains some energy.

As soon as it comes back and hits the Earth, the energy gained by the object is transferred to the surface of the Earth i. A weight lifter lifts a mass of kg with a force N to the height of 5 m. What is the workdone by the weight lifter? What is the workdone by the gravity? What is the net workdone on the object? Therefore, the work done by the weight lifter,.

When the weight lifter lifts the mass, the gravity acts downwards which means that the force and displacement are in opposite direction. The net workdone or total work done on the object. Work done,. Will they have same kinetic energy? Will they have same speed? The kinetic energy of the mass is given by. The kinetic energy of the heavier object has lesser kinetic energy than smaller mass. Calculate the potential energy stored in the object.

Where does this potential energy come from? What external force must act to bring the mass to that height? Here the positive sign implies that the energy is stored on the mass.

This potential energy is transferred from external agency which applies the force on the mass. From the definition of potential energy, the object must be moved at constant velocity. So the net force acting on the object is zero. On which spring will more work has to be done if they are stretched by the same force? The work done on the springs are stored as potential energy in the springs. Thus, more work is done on B than A. A body of mass m is attached to the spring which is elongated to 25 cm by an applied force from its equilibrium position.

## Mechanics: Work, Energy and Power

Thanks for visiting our website. Our aim is to help students learn subjects like physics, maths and science for students in school , college and those preparing for competitive exams. All right reserved. All material given in this website is a property of physicscatalyst. A body fall from height H. Which of these relation is true for t 1 and t 2 a.

## work and energy problems with solutions pdf

Question 6. The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative: a Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket, b Work done by gravitational force in the above case, c Work done by friction on a body sliding down an inclined plane, d Work done by an applied force on a body moving on a rough horizontal plane with uniform velocity, e Work done by the resistive force of air on a vibrating pendulum in bringing it to rest.

How much work is done by the force? Problem : A ball is connected to a rope and swung around in uniform circular motion. The tension in the rope is measured at 10 N and the radius of the circle is 1 m. How much work is done in one revolution around the circle? Problem : A crate is moved across a frictionless floor by a rope THAT is inclined 30 degrees above horizontal.

Give an example of something we think of as work in everyday circumstances that is not work in the scientific sense. Is energy transferred or changed in form in your example? If so, explain how this is accomplished without doing work. Give an example of a situation in which there is a force and a displacement, but the force does no work. Explain why it does no work.

*Renatta Gass is out with her friends. Misfortune occurs and Renatta and her friends find themselves getting a work out.*

- Не поможете. - Опоздала на самолет. Она кивнула. - Потеряла билет.

И улыбнулся, едва сохраняя спокойствие. - Ты сочтешь это сумасшествием, - сказал Беккер, - но мне кажется, что у тебя есть кое-что, что мне очень. - Да? - Меган внезапно насторожилась.

Другого нет и не. Двадцать миллионов долларов - это очень большие деньги, но если принять во внимание, за что они будут заплачены, то это сущие гроши. ГЛАВА 19 - А вдруг кто-то еще хочет заполучить это кольцо? - спросила Сьюзан, внезапно заволновавшись.

*Это был Джабба.*

## 5 Comments

Jacob K.Given :.

ViesacoofesProblems: Work, Energy, Power. 1) A kg mass sliding on a frictionless horizontal surface at m/s hits a spring that is attached to a wall. The spring has a.

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