Question

a 3200 kg moving at speed of 40 m/s collides head on with another 30000 kg jeepney at rest . the moving jeepney come to rest and the other jeepney moves with a speed of 40 m/s . what is the total momentum after collison?

Answer 1

As you know, momentum is the product of mass and velocity of body .
question asked , total momentum after collision,
After collision , one body will be rest and other body will be in motion with 40m/s
Hence, total momentum after collision = 3000 kg × 0 { because first Body be rest } + 30000 × 40 { second body moves with 40 m/s }
= 1.2 × 10⁶ Kgm/s

But we total momentum in collision is conserved
But here, initial momentum = 3200 × 40 = 1.28 × 10⁵ Kgm/s
Final momentum = 1.2 × 10⁶ Kgm/s
e.g., initial momentum ≠ final momentum
Hence, this question is not perfect question .


Well you can say total momentum after collision is 1.2 × 10⁶ kgm/s

Answer 2

Given :
mass of first body=m1=3200kg
speed =u1=40m/s
mass of second object -m2=30000kg
speed of second object=u2=0 m/s

Total initial momentum before collision=m1u1+m2u2=3200x40=128000 kgm/s

final speed of first object is =v1= 0 m/s
final speed of second object =v2=40m/s

Momentum after collision=3200x0+30000x40
=1200000kg m/s

According to law of conservation of momentum,total momentum before collision = total momentum after collision. but in this equation total momentum before collision is not equal to total momentum after collision.

But still as question asked is final momentum.. we can say it is 1200000kg m/s=12x10⁵kgm/s