Question

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

(i) a butterfly of mass 1.0 g that flies upward at a rate of 0.5 m s^–1. 

(ii) a 250 g squirrel climbing up on a tree at a rate of 0.5 m s^–1.

Answer 1

(i) Power = mg × velocity, g = 10 m s^–2 

= 1/1000 ×10× 0.5W 1000 = 0.5 W  

=0.5/100 W = 5 x 10^-3 

(ii) Power = 250/1000 ×10× 0.5 W 

= 1/ 4x10x0.5 = 1.25 W Hence, the power with which the squirrel is climbing is much higher than that of a butterfly flying.