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A boy of mass 45 kg running 6 m/s jumps onto a 30 kg trolley moving in the same direction at 1.5 m/s. Their common velocity will be: A. 4.0 m/s B. 4.2 m/s C. 6.5 m/s D. 8.3 m/  
Asked by nishitatrambadia | 21 Oct, 2021, 09:38: AM
answered-by-expert Expert Answer

Using conservation of momentum

MV+mv = (M+m)v'

Where :
M- Mass of the boy= 45 kg
m- mass of the trolley = 30 kg
V- velcoity of the boy = 6 m/s
v- velocity of the trolley= 1.5m/s
v' - common velocity = x

(45 + 30) x = (45 x 6 + 30 x 1.5)

v' = x= 4.2 m/s

Hence, the common velocity of the 4.2 m/s.

Correct option is B

Answered by Shiwani Sawant | 21 Oct, 2021, 11:56: AM

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