Category Archives: Linear Momentum and Collisions

Two-Liter Etoh Rocket

Demo: ME-N-TL
Pira Index: 1N 22.00

 Lab Equipment  Directions
  1.  special 2 liter plastic soda bottle
  2. 20′ length of heavy nylon string
  3. ethyl alcohol
  4. torch
Caution: Using too much alcohol can melt the bottle.
If running a string is not practical, the bottle can be placed on bottom runners made of 2 straws so that it can slide across the floor.
  1.  Tie the string across a span of the room (i.e. from the faucet to a higher point on the wall).
  2. Put a dropper full of ethyl alcohol into bottle. Holding your finger over hole in lid, swirl alcohol to coat inside of bottle with alcohol. Hang bottle, by its attached hooks, over the string (bottle opening should face faucet).
  3. Stand back and quickly ignite the alcohol mixture with the torch.


Ping Pong Ball Launcher

Demo: ME-N-PP
Pira Index: 1N 22.20

 Lab Equipment  Directions
  1.  bottle with piezoelectric igniter
  2. special ping pong ball
  3. isopropyl or ethyl alcohol
  1.  Put 1/2 dropper full of alcohol in the bottle. Too much alcohol is unsafe!
  2. Lightly push the ping pong ball into the mouth of the bottle and swirl the alcohol around in the bottle.
  3. Aim at the side of the room and push the button on the piezoelectric lighter.
  4. Blow fresh air in between shots (1/2 dropper is enough for several shots).


Happy-Sad Pendulum

Demo: ME-N-HP
Pira Index: 1N 30.55

 Lab Equipment  Directions
  1.  happy sad balls
  2. small lab stand
  3. pendulum clamp
  4. block of wood
  1.  Show that the balls appear to be identical in size, weight, and appearance.
  2. Place the block of wood next to the balls.
  3. The balls should touch the block about a quarter of the way from the top.
  4. Draw back the balls one at a time to an angle of 90 degree and release.
  5. One of the balls should cause the block to tip, the other should not.

click on image to play gif animation

Hand Hammer

Demo: ME-N-HH
Pira Index: 1N 10.00

 Lab Equipment  Directions
  1.  set of boards glued together to make a platform
  2. single 3/4″ pine board large enough to span across the platform
  3. small board for protecting your hand
  4. 3″ nail stuck through post-it pad
  5. heavy cloth glove
  1.  Put on the glove and hold the small board against your palm. Put the hand of the nail between two fingers with the head resting against the small board as shown.
  2. Raise your hand above the board at which you’re aiming the nail and bring your hand down fast and hard, relying on the inertia of the hand to drive the nail through.


Bi-Ball Demo

Demo: ME-N-BB
Pira Index: 1N 30.64

 Lab Equipment  Directions
  1.  basketball
  2. black rubber ball
  3. 2 balls on axle
  1.  Bounce both balls from the same height. Note how high they bounce back.
  2. Ask if there is a way to make them bounce higher without changing the height or initial velocity.
  3. Place black ball atop basketball.
  4. Drop vertically to a hard surface.
  5. The black ball will bounce upwards with high velocity.