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Friction and momentum...

I just keep getting a stupid answer for this :/

Two cars, travelling in the same direction, skid on a patch of smooth level ice. Car A, of mass 1400kg, skids straight into the back of car B, of mass 1000kg. The two cars become entangled after the impact and continue to move in the same straight line.

Before impact, car B is moving with a speed of 8m/s.
After impact, both cars are moving with a speed of 15m/s.

a) was to calculate the speed of Car A before the collision to which I got 20m/s.

b) is where I'm stuck - After the collision, the cars leave the patch of ice and continue skidding along the road. They come to rest in a distance of 20m after leaving the ice. Calculate the average frictional force acting on the cars as they come to rest.

Please help :smile:

Thank you.

Reply 1

abstraction98

This is quite straightforward. You know the speed the entangled cars move off with and how far they stop the collision.

Therefore you can find the acceleratin.

Using f=ma and using the mass of the two cars you can find the average force :smile:

Hope this helps

Reply 2

Kiki.J

Thank you