a 1. Write true or false for each statement : Column (a) Non ca (a) The frictional force acts in the direction of motion of body. False (b) Like p (c) Conta (b) The unit of weight is kilogram. False (d) Mass (c) A force can change the direction of motion (e) Weig of a moving body. Deve (f) Frict (d) A force increases the mass of the body Ans: (a)-(ii when applied on it. False 4. Selec (e) The force of friction is always disadvantageous. False (f) The sliding friction is more than the rolling friction. Due (g) Liquids offer more friction than the gases.pue (h) A wet oily road offers more friction than a dry rough road.al nsTrue. (c) (f. (9 () o
Answers
Answer:
Work done is considered positive when the displacement is in the same direction as that of the applied force and negative when the displacement is in the opposite direction of applied force.
(a)Positive
In the given case, force and displacement are in the same direction. Hence, the sign of work done is positive. In this case, the work is done on the bucket.
(b) Negative
In the given case, the direction of force (vertically downward) and displacement (vertically upward) are opposite to each other. Hence, the sign of work done is negative.
(c) As force and displacement are in opposite directions, work done is negative.
(d) As force and displacement are in the same direction, work done is positive.
(e) As force and displacement are in opposite directions, work done is negative.