Question

(a) The S.I. unit of work is

(i) second (ii) metre

(iii) joule (iv) Newton.

(b) No work is done by a force if the body

(i) moves in direction of the force

(ii) does not move

(iii) moves in the opposite direction

(iv) none of these

(c) Two coolies A and B do dome work in time 1 minute and 2 minutes respectively. The power spent is

(i) same by both coolies

(ii) is more by coolie A than by B

(iii) is less by coolie A than by B

(iv) nothing can be said

(d) The expression of power P is

(i) P = mgh (ii) P = $\frac{1}{2}m{v}^2$

(iii) P = $F\times d$ (iv) P =$F\times \frac{d}{t}$

(e) 1 H.P. is equal to

(i) 1 W (ii) 1 J

(iii) 764 J (iv) 746 W

(f) When a boy doubles his speed, his kinetic energy becomes

(i) half (ii) double

(iii) four times (iv) no change

(g) A boy lifts a luggage from height 2 m to 4m. The potential energy will become

(i) half (ii) double

(iii) one- third (iv) one - fourth

Answer 1

(a) The S.I. unit of work is - (iii) joule
(b) No work is done by a force if the body - (ii) does not move
(c) Two coolies A and B do dome work in time 1 minute and 2 minutes respectively. The power spent is - (ii) is more by coolie A than by B
(d) The expression of power P is - P =$F\times \frac{d}{t}$
(e) 1 H.P. is equal to - (iv) 746 W
(f) When a boy doubles his speed, his kinetic energy becomes - (iii) four times
(g) A boy lifts a luggage from height 2 m to 4m. The potential energy will become - (ii) double