Question

boy of mass 40 kg climb up the stairs and reach of the roof at the height 8 cm in 5 seconds calculatei) the force of gravity acting on the boy ii) the work done by him against the force of gravityiii)the power spend by boy (take g10ms-2)

Answer 1

(i)
Force of gravity acting on the boy = mg
= 40 * 10
= 400 N

(ii)
Work done by him = mgh
= 40 * 10 * 0.08
= 32 J

(iii)
Power = Work / Time
= 32 / 5
= 6.4 Watt

Answer 2

Answer:

(i) F=ma

=40 * 10

=400 N

(ii) W =mgh

=40*8*10

=3200

(iii) P=W/t

=mgh/t

=3200/5

=640 Watt

Explanation: