# Inelastic collision

Chica1975

## Homework Statement

A car of mass 950kg travelling at 60km/h in an easterly direction collided perfectly inelastically with another care of mass 1250kg travelling at 55.0km/h in a northerly direction. The design of the smaller care incorporated safety features which ensured that any occupants came to rest relative to the care in a tie of 250m/s. Both vehicles had one occupant of 75.0kg

calculate the velocity of the wreckage immediately after the collision.

Use conservation of momentum to determine the change in momentum of both vehicles

## Homework Equations

m1v1 + m2v2 = m'1v'1 + m'2 v'2
I am not sure if the kinetic energy equation fits here too?
.5 m1 v1 E2 + .5 m2 v2 E2 = .5 m1 v'1E2 + .5 m2v'2E2
r= square root (xE2 +yE2)
p=mv

## The Attempt at a Solution

I converted all the km/h to m/s
I calculated the momentum of each vehicle p=mv (I also included the weight of the driver for each). Using the answers I found the resultant.
I then rearranged the equation to find v and got the right answer in it.

I am now really struggling with the conservation of momentum - these always get me out. I can't seem to use the right equation and am just blank.

Can someone let me know = thank you. :)

Hi Chica1975! you don't need, and mustn't use, conservation of energy! 