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A car of mass 400 kg and travelling at 7...

A car of mass 400 kg and travelling at 72 km/h crashes into a truck of mass 4000kg and travelling at 9 km/h in the same direction. The car bounces back at a speed of 18 km/h. The speed of the truck after the impact is

A

`9 km//h`

B

`18 km//h`

C

`27 km//h`

D

`36 km//h`

Text Solution

Verified by Experts

The correct Answer is:
B
Applying the law ofconservation of momentum,
`400 xx 20 + 4000 xx 2.5=-400 xx 5 + 4000 v_2`
`implies v_2 = 5m//sec = 5 xx 18/5 km//h = 18 km//h`
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