(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 = 12mv2 (iii) P = F×d (iv) P =F×dt (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