Education Standards

Demonstration Videos

Demonstration Videos

Overview

Video demonstration experiments show the laws and concepts in action.

Inelastic vs Elastic Collision

For our demonstration of collision, we have two smart carts of equal masses that send data to our iPad. This data can be used to verify the conservation of linear momentum. The velocity vs time graphs on the top left corner represent the corresponding colored cart. For our first experiment, the moving red cart experiences an almost elastic collision with the blue cart initially at rest. Most of the red cart’s momentum is transferred to the blue cart. We double the blue cart’s weight and repeat the experiment. This results in both carts having some non-zero velocity after the collision.

For our second experiment, we push the red cart into the blue cart and they move as a single object after collision (inelastic collision). This results in the two carts moving with a final velocity less than the red cart’s initial velocity.

Inelastic vs Elastic Collision

 

Newton’s Cradle

Newton's cradle is a great demonstration of the conservation of linear momentum and the conservation of energy. When one sphere at the end is lifted and released, it will strike the stationary spheres and come to nearly a complete stop, transmitting most of its energy and momentum to the last sphere. This experiment can be done with more than one ball being lifted, if two are lifted, then two balls swing out on the opposite side.

Newton’s Cradle

 

Galilean Cannon

The Galilean Cannon is an example of the conservation of linear momentum. If we stack the tennis ball on top of the basketball and drop them, the descending tennis ball collides with the basketball which is already moving up after bouncing off the floor. Since the basketball is much heavier, the tennis ball gets a large kick from the collision, making it fly higher than its initial height. We repeat the experiment with four plastic balls, starting with the smallest on top and the largest in the bottom. The result is three consecutive collisions, in which the lightest top ball receives the largest kick. 

Galilean Cannon

 

LN2 Rocket

The rocket on a cart has a hole, into which we pour liquid nitrogen, and an exhaust valve. Once we pour the liquid nitrogen into the rocket, the liquid nitrogen will evaporate and exit  through the exhaust valve, carrying linear momentum in the process. According to the momentum conservation, the cart is pushed in the opposite direction. 

LN2 Rocket

 

Double Cone on Rails

This demonstration seems to be a result of magic. But, the physics behind it is quite simple. The double cone is placed on an incline made out of v-shaped rails. The double cone seems to be rolling uphill, but its center of mass is actually moving downwards. 

Double Cone on Rails

 

Inertia with Soda Cans

When the cloth is pulled slowly, the force of friction between the soda cans and cloth has enough time to overcome the soda cans' inertia and give them a nonzero momentum, causing the cans to fall. When the cloth is pulled quickly the impulse due the force of friction is too small, and soda cans remain at rest.

Inertia with Soda Cans