VT KTU Feb. 25th exhibit - Catapults and Newton’s Three Laws of Motion

Exhibit by Sally Farrell

Craig County 4-H

Catapults and Newton’s Three Laws of Motion

We will exhibit three different kinds of catapults (wooden, Lego NXT, and home-made) and see how these catapults demonstrate Newton’s three Laws of Motion:

1. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it:

Ø The projectile rests in the catapult until launched and then travels until it is acted on by gravity and lands on the ground.

2. The acceleration of an object depends directly upon the force acting upon the object, and inversely upon the mass of the object. As the force acting upon an object is increased, the acceleration of the object is increased. As the mass of an object is increased, the acceleration of the object is decreased.

Ø The catapult exerts a given amount of force depending on how far the bucket is cranked back. The mass depends on the payload.

3. For every action there is an equal and opposite reaction.

Ø The catapult will experience exactly the same force as the thrown object but in the opposite direction. It will begin to move backwards.