Question

A girl having mass of 35 kg sits on a trolley of mass 5 kg. The trolley is given an initial velocity of 4 m s^–1 by applying a force. The trolley comes to rest after traversing a distance of 16 m. 

(a) How much work is done on the trolley? 

(b) How much work is done by the girl?

Answer 1

u = 4 m s^–1 , 

v =o, s = 16 m 

a = v² - u² / 2s = - 16 / 2 x 16 = − 1/ 2  m s²

Force = m a = 40 × (- 1/2 ) = - 20 N 

Work done on the trolley = 20 N ×16 m = 320 J 

Work done by the girl = 0 J