Work and Energy Worksheet-5

Work and Energy Worksheet-5

 

  1. Write an expression for the kinetic energy of a body of mass m moving with a velocity v.

 

  1. If the speed of a body is halved, what will be the change in its kinetic energy?

 

  1. On what factors does the kinetic energy of a body depend?

 

  1. Which would have a greater effect on the kinetic energy of an object : doubling the mass or doubling the velocity?

 

  1. How fast should a man of 50 kg run so that his kinetic energy be 625 J?

 

  1. State whether the following objects possess kinetic energy, potential energy, or both:

A man climbing a hill

 

  1. State whether the following objects possess kinetic energy, potential energy, or both:

A flying aero plane

 

  1. State whether the following objects possess kinetic energy, potential energy, or both:

A bird running on the ground

 

  1. State whether the following objects possess kinetic energy, potential energy, or both:

A ceiling fan in the off position

 

  1. State whether the following objects possess kinetic energy, potential energy, or both:

A stretched spring lying on the ground.

 

  1. Two bodies A and B of equal masses are kept at heights of h and 2h respectively. What will be the ratio of their potential energies?

 

  1. What is the kinetic energy of a body of mass 1 kg moving with a speed of 2 m/s?

 

  1. Is potential energy a vector or a scalar quantity?

 

  1. A load of 100 kg is pulled up by 5 m. Calculate the work done, (g = 9.8 m/s2)

 

  1. State whether the following statement is true or false :

The potential energy of a body of mass 1 kg kept at a height of 1 m is 1 J.

 

  1. What happens to the potential energy of a body when its height is doubled?

 

  1. What kind of energy is possessed by the following?

A stone kept on roof-top.

 

  1. What kind of energy is possessed by the following?

A running car.

 

  1. What kind of energy is possessed by the following?

Water stored in the reservoir of a dam.

 

  1. What kind of energy is possessed by the following?

A compressed spring.

 

Answer:

  1. Kinetic energy = (1/2)mv2

Where m = mass of the body And v = velocity of the body (speed of the body)

 

  1. Becomes one-fourth

Kinetic energy = (1/2)mv2 If speed is halved KE will be one fourth.

 

  1. Mass and speed

Kinetic energy = (1/2)mv2

 

  1. Doubling the velocity

Since Kinetic energy = (1/2)mv2

 

  1. 5 m/s

 

  1. Both kinetic energy and potential energy

 

  1. Both kinetic energy and potential energy

 

  1. Only kinetic energy

 

  1. Only potential energy

 

  1. Only potential energy (rather elastic potential energy)

 

  1. 1:2

Using PE = mgh

 

  1. Using the formula

Kinetic energy = (1/2)mv2

2 J

 

  1. Scalar

 

  1. 4900 J

 

  1. False

PE = mgh so value of g is to be put

 

  1. Potential energy gets doubled

PE = mgh so if height is doubled PE is also doubled.

 

  1. Potential energy

 

  1. Kinetic energy

 

  1. Potential energy

 

  1. Potential energy