Question

A car with mass 2.0×10 3 kg traveling east at a speed of 20 m/s collides at an intersection with a2.5×10 3 kg van traveling north at a speed of 20 m/s. Find the magnitude and direction of the velocity of the wreckage after the collision, assuming that the vehicles undergo a perfectly inelastic collision and assuming that friction between the vehicles and the road can be neglected. (they stick together in the collision). Just like the example in class, with slight changes. I have no idea where to start or how to do this may someone please help me. Thank you.

Answer 1

When analyzing inelastic collisions, we need to consider the law of conservation of momentum, which states that the total momentum, p, of the closed system is a constant. In the case of inelastic collisions, the momentum of the combined mass after the collision is equal to the sum of the momentum of each of the initial masses.

p1+p2+...=pf

In our case we only have two masses, which makes our problem fairly simple. Lets plug in the formula for momentum; p=mv.

m1v1+m2v2=(m1+m2)vf

To find the velocity of the combined mass we simply rearrange the terms.

vf=m1v1+m2v2m1+m2

Plug in the values given in the problem.

vf=(3.0kg)(1.4m/s)+(2.0kg)(0m/s)03.0kg+2.0kg

vf=.84m/s