Question

5. A boy of mass 40 kg runs up a flight of 20 stairs each of height 20 cm, (g = 10), in 10 secs.

(i) The weight of the boy is:

a) 400 N

b) 40 N

c) 400 kgf

d) 4 N

(ii) The work done is :

a) 160 J

b) 1600 J

c) 16 J

d) 16000 J

(iii) The power developed is:

a) 1.6 W

b) 16 W

c) 160 W

d) 1600 W

​

Answer 1

Answer:

Weight of the body= mg

W=40×10

w=400N

Work Done=mgh

WD=(40×10×20×20)/100

WD=16000/100

WD=160J

Power Developed=WD/T

PD=160/10

PD=16W

Hope it's Ok....