(adsbygoogle = window.adsbygoogle || []).push({}); Momentum Conservation --- so hard!

1. The problem statement, all variables and given/known data

Two automobiles collide at an intersection. One car of mass 1.4 X 10^3 kg is traveling at 45km/h ; the other car of mass 1.3 X 10^3 kg is traveling at 39km/h [E]. If the cars have a completely inelastic collision, what is their velocity just after collision?

2. Relevant equations

v1m1 + v2m2 = v(m1 + m2)

3. The attempt at a solution

Given information:

m1 = 1.4 X 10^3 kg

m2 = 1.3 X 10^3 kg

v1 = 45km/h --> 12.5 m/s

v2 = 39 km/h [E] --> 10.83 m/s

vf ' = ?

v1m1 + v2m2 = v(m1 + m2)

(12.5)(1.4 X 10^3) + (10.83)(1.3 X 10^3) = v (1.4 X 10^3 + 1.3 X 10^3 kg)

v = 11.7 m/s --> 42 km/H

But the answer that I get is wrong. So anyone please help me how to do this. Thanks.

The correct answer is 30 km/h.

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# Homework Help: Momentum Conservation - so hard!

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