Work and energy

Work and Energy Worksheet-4

1. A car weighing 1000 kg and traveling at 30 m/s stops at a distance of 50 m decelerating uniformly. What is the force exerted on it by the brakes? What is the work done by the brakes?

2. How much work is done when a body of mass m is raised to a height h above the ground?

3. State the SI unit of work.

4. Is work a scalar or a vector quantity?

5. Define 1 joule of work.

6. What is the condition for a force to do work on a body?

Work and Energy Worksheet-5

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

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

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

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

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

Work and Energy Worksheet-6

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

A stretched rubber band.

32. What are the quantities on which the amount of work done depends? How are they related to work?

33. Is it possible that a force is acting on a body but still the work done is zero? Explain giving one example.

34. A boy throws a rubber ball vertically upwards. What type of work, positive or negative, is done :    

(a) by the force applied by the boy ?

(b) by the gravitational force of earth ?