# Homework Help: Car Collision Dynamics

1. Jun 6, 2010

### kian651

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

Car A moving at 30 km/h strikes car B (stationary). The two become entangled and move together.

Find:

Common velocity after impact. V2

Average acceleration of both cars during impact.

Magnitude of the force exerted on each car during impact.

Percentage energy loss.

I found
V2: 5/55
acc A= -27.8 ACC B= 55.53

Force F=ma for each.

Energy loss= 1/2 mv^2 initial -( 1/2 mv^2 A final+ 1/2 mv^2 B final)

Is that right?

2. Jun 6, 2010

### kuruman

I can't tell without the masses of the two cars.

3. Jun 6, 2010

### kian651

lol sorry man,
A- 1800 KG
B - 900 KG

4. Jun 6, 2010

### kuruman

Your answer is not correct. To begin with, F = ma is not the issue here. The cars are not accelerating. They are moving at constant velocity until they collide. You need to conserve linear momentum. Please try again and show exactly what you did so that I can point out where you went wrong if that happens to be the case.

5. Jun 8, 2010

### Lok

Average acceleration needs a time interval... not given. Not really solvable. :P