Question

A car of mass 400kg travilling at 72 km/h crashes into a truk of mass 4000 kg and travilling at 9 km/h in same direction. The car bounce back at a speed of 18 km/h. Find the speed of the truk after the impact

Answer 1

Answer:

Let mass of car m1= 400 kg,

Initial velocity of car u1=70km/hr =19.44 m/s

Let the mass of truck m2=4000 kg

Initial velocity of truck u2 = 9km/hr =2m/s

Final velocity of car v1=18km/hr = 5m/s

 velocity of truck v2 =?

According to law of conservation of momentum. Total momentum before collision is equal to total momentum after collision.

m1×u1+m2×u2=−m1×v1+m2×v2400×19.4+4000×2.5=−400×5+4000v24000v2 =7760+10000+2000v2=4.94m/sv2=4.94×185v2=17.784km/hr

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