2. Who Has Done More Work?

WORK AND ENERGY Grade – IX

NUMERICALS

1. Calculate the work done when a force of 13 N acting on an object displaces it through 5m in the direction of force.

2. Who has done more work?

a) A force of 5N displacing an object through 3m in the direction of force or

b) A force of 8N displacing an object through 2.5 m in its direction?

3. Calculate the work done when a student weighing 400N carries a weight of 200N from the ground to a height of 15m.

4. Kinetic energy of ball of mass 50gm is 10J. Find the speed of ball.

5. A ball of mass 200 gm is thrown upwards with an initial velocity of 30m/sec. What is its kinetic energy at the highest point of its path? What is the potential energy there?

6. A coconut of mass 1.5 kg falls from a height of 8 m. What was its value of potential energy? Take g=10m/sec.

7. The motor of a pump lifts 30kg water per minute to a height of 6m. What is the power of motor? ( g=10 m/sec)

8. A tube light of 40W power is used daily for 6hrs. How many units of energy are being consumed in 30 days?

9. Calculate the work done in raising a bucket full of water and weighing 20kg through a height of 5m. ( 9.8 m/sec)

10. A load of 100 kg is pulled by 5m. Calculate the work done. (g=9.8m/sec)

11. A man whose mass is 60 kg walks up the top of a building, whose height is 10m above the street level. How many joules of work has he done? ( g=9.8m/sec)

12. A man weighing 60 kg lifts a weight of 40kg to the top of building 10 m height. Find the work done by him.(g=9.8m/sec)