• state with reason whether the work done in the following cases is postive or negative.

a. work done by a boy in pulling a toy car

b. work done in pulling a string

c. work done in dropping a stone down

d .work done in throwing a ball

e.work done in moving on a track

f. work done by a man in lifting a bucket out of well by means of a rope tied to the bucket.

g. work done by the gravitational force in the above case f .

h. work done by the frictionon a body sliding down an inclined plane .

i. work done by an applied force on a body moving on a rough horizontal plane with uniform velocity

j. work done by the resistive force of air on a vibrating pendulum to bring it to rest.

(a) Positive because pulling force and displacement are in the same direction.

(b) Positive because pulling force and displacement are in the same direction.

(c) Positive because gravitational force and displacement are in the same direction.

(d)Positive because force by us and displacement are in the same direction.

(e)Positive because force to move and displacement are in the same direction.

(f)Positive because force by man and displacement are in the same direction.

(g)Negative because gravitational force and displacement are in the opposite direction.

Try to find the remaining. Hope you understand the concept.

@Deepanjali, Good effort. Keep it up!

  • 12
  1. positive
  2. positive
  3. positive
  4. positive
  5. positive
  6. positive
  7. negative
  8. negative because displacement is in the opposite direction of friction.
  9. positive
  10. negative

I hope these are correct. If yes or no, thumbs up......

  • 6
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