List of practice Questions

A mass of 10 kg is at a point A on a table. It is moved to a point B. If the line joining A and B is horizontal, what is the work done on the object by the gravitational force? Explain your answer.

Look at the activities listed below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
• Suma is swimming in a pond.
• A donkey is carrying a load on its back.
• A wind-mill is lifting water from a well.
• A green plant is carrying out photosynthesis.
• An engine is pulling a train.
• Food grains are getting dried in the sun.
• A sailboat is moving due to wind energy.

An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and the final points of the path of the object lie on the same horizontal line. What is the work done by the force of gravity on the object?

What is the work done by the force of gravity on a satellite moving round the earth? Justify your answer.

An object of mass, m is moving with a constant velocity, v. How much work should be done on the object in order to bring the object to rest?

Calculate the work required to be done to stop a car of 1500 kg moving at a velocity of 60 km/h?

In each of the following a force, F is acting on an object of mass, m. The direction of displacement is from west to east shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative, positive or zero.

Soni says that the acceleration in an object could be zero even when several forces are acting on it. Do you agree with her? Why?

Can there be displacement of an object in the absence of any force acting on it? Think. Discuss this question with your friends and teacher.

A person holds a bundle of hay over his head for 30 minutes and gets tired. Has he done some work or not? Justify your answer.