Work and Energy Worksheet5

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

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

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

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

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

State whether the following objects possess kinetic energy, potential energy, or both:
A man climbing a hill

State whether the following objects possess kinetic energy, potential energy, or both:
A flying aero plane

State whether the following objects possess kinetic energy, potential energy, or both:
A bird running on the ground

State whether the following objects possess kinetic energy, potential energy, or both:
A ceiling fan in the off position

State whether the following objects possess kinetic energy, potential energy, or both:
A stretched spring lying on the ground.

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?

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

Is potential energy a vector or a scalar quantity?

A load of 100 kg is pulled up by 5 m. Calculate the work done, (g = 9.8 m/s^{2})

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.

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

What kind of energy is possessed by the following?
A stone kept on rooftop.

What kind of energy is possessed by the following?
A running car.

What kind of energy is possessed by the following?
Water stored in the reservoir of a dam.

What kind of energy is possessed by the following?
A compressed spring.
Answer:

Kinetic energy = (1/2)mv^{2}
Where m = mass of the body And v = velocity of the body (speed of the body)

Becomes onefourth
Kinetic energy = (1/2)mv^{2} If speed is halved KE will be one fourth.

Mass and speed
Kinetic energy = (1/2)mv^{2}

Doubling the velocity
Since Kinetic energy = (1/2)mv^{2}

5 m/s

Both kinetic energy and potential energy

Both kinetic energy and potential energy

Only kinetic energy

Only potential energy

Only potential energy (rather elastic potential energy)

1:2
Using PE = mgh

Using the formula
Kinetic energy = (1/2)mv^{2}
2 J

Scalar

4900 J

False
PE = mgh so value of g is to be put

Potential energy gets doubled
PE = mgh so if height is doubled PE is also doubled.

Potential energy

Kinetic energy

Potential energy

Potential energy