**DPP -9S101**

**DPP -9S101**

**WORK AND ENEGY**

**WORK AND ENEGY**

1. Define Work. What is 1 Joule energy?

2. 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?

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

4. 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.

5. 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.

6. 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.

7. A porter lifts a luggage of 15 kg from the ground and puts it on his head 1.5 m above the ground. Calculate the work done by him on the luggage.

8. What are the situation in which work done is zero?