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Question
A girl having a mass of 35 kg sits on a trolley of mass 5kg. The trolley is given an initial velocity of 4ms-1 by applying a force. The trolley comes to rest after travelling a distance of 16 m.
(a) How much work is done on the trolley ?
(b) How much work is done by the girl ? 35 kg 5 kg 4 m/s 16 m
reply fast. also check the previous portions
A girl having a mass of 35 kg sits on a trolley of mass 5kg. The trolley is given an initial velocity of 4ms-1 by applying a force. The trolley comes to rest after travelling a distance of 16 m.
(a) How much work is done on the trolley ?
(b) How much work is done by the girl ? 35 kg 5 kg 4 m/s 16 m
reply fast. also check the previous portions
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Solution
Given that
mass of girl = 35 kg
mass of trolley = 5 kg
Total mass, m = (35 + 5) = 40 kg
u = 4 m/s, v = 0, s = 16 m.
Using kinematics equation, v2 = u2 + 2as
⇒ 0 = (4)2 + 2a (16)
⇒ 32a = –16
⇒ a = –0.5 m/s2
Force exerted on trolley, F = ma = 40 × 0.5 = 20 N
(a) Work done on trolley W = FS = (20 N) (16 m) = 320 J
(b) Work done by the girl, W = FS
= (mass of girl) × retardation × S
= 35 × 0.5 × 16
= 280 J
Given that
mass of girl = 35 kg
mass of trolley = 5 kg
Total mass, m = (35 + 5) = 40 kg
u = 4 m/s, v = 0, s = 16 m.
Using kinematics equation, v2 = u2 + 2as
⇒ 0 = (4)2 + 2a (16)
⇒ 32a = –16
⇒ a = –0.5 m/s2
Force exerted on trolley, F = ma = 40 × 0.5 = 20 N
(a) Work done on trolley W = FS = (20 N) (16 m) = 320 J
(b) Work done by the girl, W = FS
= (mass of girl) × retardation × S
= 35 × 0.5 × 16
= 280 J
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