Question

A boy of mass 40kg climbs up the stairs and reaches the roof at a height 8m in 5s. Calculate: (i) The force of gravity acting on the boy, (ii) The work done by him against gravity, (iii) The power spent by the boy. Take g = 10 ms^-2

April 8, 2024

Answer

m = 40 kg

h = 8 m

t = 5 s

(i) Force of gravity acting on the boy

F = mg = 40 × 10 = 400 N

(ii) Work done against gravity

W = F × S = 400 × 8 = 3200 J

(iii) Power spent = $3200\over 5$ = 640 W

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