Question

Compare the power at which each of the following is moving upwards against the force of gravity? (given g = 10 m s^–2)

a 250 g squirrel climbing up on a tree at a rate of 0.5 ms^–1.

Answer 1

Mass of squirrel, ms = 250 g = 0.25 kg

Speed, vs = 0.5 m s⁻¹

Force of gravity on squirrel,

Fs = msg = 0.25 x 10

= 2.5 N

Power, P_s = F_s.v_s

= 2.5 N × 0.5 ms⁻¹

 = 1.25 W

Hence, the squirrel exerts more power in climbing than a butterfly exerts in flying at the same rate.