# Truck Launch!

## Demonstration of the principle of action - reaction: Newton’s Third Law

### Method:

1. Place spring on the bed of one of the toy trucks.
2. Compress the spring against the back of the truck cab and place the weight behind it.
3. Tie the weight to the truck cab, holding the spring in the compressed position. (You will probably need someone to help you with this step.)
4. Set the truck down on a smooth, flat, level surface.

CAUTION

CLEAR THE AREA BEHIND THE TRUCK!! THAT WEIGHT WILL FLY!!

5. Cut the string. Describe and explain what happens.

## Options:

1. Experiment with using a smaller or larger truck.
2. Experiment with using a smaller or larger weight.
3. With assistance from an adult, experiment with using a stronger spring.

## Cheap & Dirty

The Truck Launch is the fun way to demonstrate Newton's Third Law. You may be thinking "it's a simple law, there must be a simpler way". You're right. There is:

1. Blow up a balloon.
2. Let it go.

This is also a great demonstration of what your rocket will do with the fins removed.

Back to Newton's Laws