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State whether True or False.
(i) Work is said to be done when a force is applied, even if the object does not move.
(ii) Lifting a bucket vertically upward results in positive work done on the bucket.
(iii) The SI unit for both work and energy is joule (J).
(iv) A motionless stretched rubber band has kinetic energy.
(v) Energy can change from one form to another.
Show Answer
(i) False — work needs a displacement, not just a force.
(ii) True — force (up) and displacement (up) are in the same direction.
(iii) True — both are measured in joules.
(iv) False — a motionless stretched band has potential energy, not kinetic.
(v) True — energy can change from one form to another.
| Statement | True / False | Why |
|---|---|---|
| (i) work is done even if the object does not move | False | W = F × s. If s = 0, then W = 0 — a force alone is not work. |
| (ii) lifting a bucket up → positive work | True | Force (up) and displacement (up) are in the same direction. |
| (iii) SI unit of work and energy is the joule | True | Both are measured in joule (J); 1 J = 1 N × 1 m. |
| (iv) a motionless stretched rubber band has kinetic energy | False | It is not moving — it stores potential energy, not kinetic. |
| (v) energy can change from one form to another | True | Electrical → light, chemical → mechanical, and so on. |
