M.8(1) - SMALL REACTION CARTS

Various sets of dynamics carts are available: all of them are about 20 cm long and 500 grams in weight, with low-friction ball-bearing wheels. In one set the carts have strong horse-shoe magnets attached on top of them. All the others have built-in spring plungers. The carts can be held together by a string loop or hook and loop fasteners. Burning the string loop or activating the trigger button launches each cart in the opposite direction. Different weights can be added to the carts to observe different reactions.

M.8(2) LARGE REACTION CARTS

Two large carts can be used to show conservation of momentum. Two volunteers stand on the carts facing each other. When the push on the other's hands, their velocities will be inversely proportional to their weights -- choose volunteers with very different weights.

M.8(3) - JET PROPULSION

Sitting on a skateboard, a volunteer holds a fire extinguisher and fires up. The fire extinguisher works as an engine moving the cart. It is also a good demonstration of Newton's Third Law.

M.8(4) - SUPER BALL COLLISION

Two rubber balls of different sizes, connected by a string but not attached, are dropped from any height. The larger ball is about three times more massive than the smaller one. After their collision with the ground, the lighter ball retains most of the momentum of the system, this bouncing very high.

We also have the "Ninja Balls". It has five super balls of different masses staked on a rod. Drop it from a height of one meter and the top ball may rebound as high as 10 meters!

M.8(5) - COLLISION BALL APPARATUS

The end ball is swung at the others. It is stopped upon impact but its momentum is carried through all the others balls up to the first one, which swings out with the original velocity. If two balls are swung, two will swing at the other end and etc. Sets of various sizes are available, from 30 cm tall to 8 cm tall. There is also a very large (80 cm tall) set which only two balls (6 cm diameter each) and a regular sized set but with two balls of different sizes.

It illustrates conservation of momentum and kinetic energy as well at Newton's Third Law.

M.8(6) - DEAD BALL - LIVE BALL

Two balls identical in shape and color, but while the dead ball has a very small repulsive modulus, the live ball rebounds very well. Drop both balls from the same height -- the live ball bounces very high but the other one barely gets off the floor.