Question

a car of mass 400 k travelling at 72 kmph crashes into a truck of mass 400 kg and travelling at 9 kmph in same direction. the car bounces back at a speed of 18 kmph. find the speed of the truck after the impact​

Answer 1

Answer:

It's 63kmph.

Explanation:

Momentum of the car =28800 kg.m/s

". ". ". truck=3600 kg.m/s

Total momentum of car and truck= 28800+3600

= 32400 kg.m/s

(everything above are of before collision / crash.)

Now after collision/crash.,

Momentum of car= 7200 kg .m/s

Momentum of truck= mass of truck×velocity of the truck.

let velocity of the truck be v.

then ,

momentum= 400 v kg.m/s

Total momentum = 7200+400 v

Now according to the law of conservation of momentum:

Total momentum before=Total momentum after

32400 =7200+400 v

400 v= 32400-7200

400 v=25200

v =25200/400

v=63 m/s

therefore, velocity of the truck after the impact will be 63m/s .

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