# Forces and acceleration of truck and car collision

1. Dec 13, 2011

### cheerios456c

A very large truck collides head on with a small car. At the instant of collision the force of the truck on the car is _________ the force of the car on the truck and the magnitude of the acceleration of the truck is __________ the magnitude of the acceleration of the car.

I know that the answer is equal to, less than but I'm having trouble understanding why. If someone could explain to me why this is, I would greatly appreciate it.

Thanks!

2. Dec 13, 2011

### Delphi51

Look up Newton's Third Law.
You'll need the formula relating force to acceleration to understand the second part.

3. Dec 13, 2011

### Simon Bridge

Welcome to PF.

The first answer "equal to" is from Newton's laws - usually the third one.
The second one "less than" is due to conservation of momentum... but can be understood from the first answer if you consider that the forces are equal but the masses are not. (Newton's second law.)

It looks like you are learning about Newton's Laws of motion.