Table of Mechanics

Mechanics (1M): Work and Energy

Mechanics (1Q): Rotational Dynamics

Lecture Demonstrations

Linear Momentum

PIRA classification 1N

101 Demonstrations listed of which 65 are grayed out

Grayed out demonstrations are not available or within our archive and are under consideration to be added.

1N10. Impulse and Thrust


Demonstration Name



Collision Time Pendulum

Two metal wire bifilar pendulums are suspended as part of a circuit to measure contact time on a counter.


Time of Contact

A steel ball suspended from a conducting wire hits a vertical steel plate and the electrical signal gives time of contact.


Fleeting Event Timer

Hitting two hammers together gates a fast oscillator to a counter.


Contact Time by Oscillator

A ball swings against a plate completing a circuit allowing an oscillator to feed a counter to measure collision time.


Measuring Impulse

A pendulum strikes a piezoelectric crystal and generates a voltage spike which is viewed on an oscilloscope.


Measuring Impulse by Induction

A pendulum strikes a magnet moving it in a coil inducing a current that deflects a galvanometer.


Silicone Ball on Blackboard

Throw a silicone ball at a dirty blackboard, measure the diameter of it's imprint. Then, place weights on the silicone ball until it deforms to the same diameter as the imprint. Calculate the interaction time.


Deform Clay

Drop a 50 g mass on some softened clay, then add masses slowly to another blob of clay until the depression is equal.


Egg in Sheet

Throw an egg into a sheet held by two students.


Drop Egg in Water

It doesn't break.


Pile Driver with Foam Rubber

Break a bar of plexiglass or sheet supported on two blocks with a pile driver. Add foam rubber to a second bar or sheet and it doesn't break.


Car Crashes

A cart rolls down an incline and smashes a beer can against a brick wall. Four interchangeable bumpers are used to vary the impulse.


Car Safety on the Air Track

Models of a person with a head, seat belt and a head rest are placed on an air track cart.


Auto Collision Videodisc

Show segments of the video disc.


Impulse Acceleration Track

A mass on a right angle lever imparts a known variable impulse to a cart on a track and the final velocity is measured.


Karate Strikes

Analysis of karate strikes and description of breaking demonstrations.


Water Stream Impulse

The force created by a momentum change in a fine water stream is calculated using measurements obtained with a large scale impulse balance. Construction details.


Jet Velocity by Impulse

The impulse supplied by the counterweight equals the loss of horizontal momentum of a jet of water. The exit velocity of the water jet is then calculated and checked by measuring range.


Model Rocket Impulse

Using solid fuel model rocket engines as an impulse generator, demonstrate the impulse-momentum theorem by measuring the final velocity.


Model Rocket Thrust

A device provides a method of measuring the thrust of a model rocket engine and recording it on graph paper. Impulse is calculated. Clever.


Model Rocket Thrust

An apparatus designed to measure the thrust of a rocket is used to check the manufacturer's specifications.


Fire Extinguisher Thrust

Measure the thrust of a fire extinguisher.


Measuring Impulse

Complete treatment of the fire extinguisher cart to get exhaust velocity and average thrust for a variable mass system.


Air Cart Rocket Thrust

A device (diagram) measures thrust of a gas propelled air cart. Speed and acceleration are determined by strobe photography.


Thrust Pendulum Independent of Medium

A rocket pendulum maintains the same angle of recoil in air or water showing thrust is independent of medium.

1N20. Conservation of Linear Momentum


Demonstration Name



Seesaw Center of Mass

A string holding two carts with opposing horseshoe magnets is burned and they remain balanced on a board as they repel. The carts can be loaded unequally.


Rolling Ball on Air Cart

A ball rolls down a small inclined plane mounted on an air track glider. Watch the glider start and stop.


Car on Rolling Board

Use a radio-controlled car on the board on a series of rollers.


Train on Rolling Board

A straight train track is mounted on a movable board. Changing the weighting of the train will change the relative velocities of the train and track. Use a circular track for conservation of angular momentum.


Car on Road

A drawing board rides on perpendicular sets of steel rods to give 2D freedom of motion. Set a toy wind up car on it.


Train on Air Track

An HO gauge train and 36" track mounted on a air cart. See 1&idtype=cvips&doi=10.1119/1.1971014&prog=normal.



Using a scissors, cut a string holding a compressed spring between two air gliders.


Reaction Carts with Lights

Two carts of equal mass sit in the center of an air track. Then, they are accelerated away from one another by magnets, explosives, springs etc. Because the carts are of the same mass, given the same velocity, and begin in the middle of the track, they reach the ends of the track at the same time. A photogate or some other mechanism signals their arrival by lighting a light bulb.


Recoiling Magnets

Hold two small horseshoe magnets together on an overhead projector and observe the recoil.


Elastic band Reaction Cars

Pull apart two carts of unequal mass attached to each other with an elastic band. They accelerate toward one another.


Exploding Pendulums

Two large pendulums of unequal mass are held together compressing a spring. When the spring is released, two students mark the maximums.


Exploding basketballs

Explode a firecracker between a light and heavy basketball that are suspended near the ceiling. See AJP 41(7),922.


Big Bertha

A dry ice cannon is mounted on model railroad tracks. Average velocity of the recoiling cannon and projectile are timed.



Explode a firecracker in an iron block 4x4x2" pieced together from three sections. The center of mass may move a noticeable amount due to friction. See AJP 34(8), 707 for the demo and AJP 35(4), 359 for a comment about friction.


Air Track Center of Mass Collision

An inelastic air track collision with a cart and a spring coupled cart system. See AJP 57(2), 182.

1N21. Mass and Momentum Transfer


Demonstration Name



Floor Carts and Medicine Ball

Two people on roller carts throw a medicine ball to each other or to at the wall.


Catapult from Cart to Cart

Catapult a ball from one cart to another. The ball needs to be quite heavy and the carts need low friction wheels.


Thrust Cars

Conservation of momentum of a thrust producing stream on water is shown by two carts on a track: one has a nozzle, the other a bucket to catch the water.


Ballistic Air Glider

Shoot a .22 into a wood block mounted on an air glider. Use a timer to determine the velocity. See the University of Minnesota website.


Drop Mass on Cart

A cart passes by a device that adds mass to the cart. Timers measure the velocity before and after the transfer.


Jump on the Cart

Run at constant velocity and jump on a roller cart.


Air Track Ball Catcher

Shoot a stream of balls at a moving air cart until the cart stops.

1N22. Rockets


Demonstration Name



Historical Note

An article claims rockets will not work in space because there is nothing to push against. See TPT 20(2), 107.


Fire Extinguisher Rocket

Hold a CO2 fire extinguisher while seating on a scooter cart.



Dual-mounted CO2 fire extinguishers are on the back of a tricycle.


Rocket video

Show video of a rocket or shuttle launch.


Water Rocket

Pump a toy water rocket the same number of times, first with only air, and then with water.


Air Track Rocket

Air from a rubber balloon propels an air cart.


Balloon Rocket

"Balloon rockets" are available at toy stores. Normal balloons move chaotically.


CO2 Rocket Car

Cartridges of CO2 are used to propel small automobiles or projectiles.


CO2 Rocket to the Moon

A CO2 powered rocket rides a wire across the classroom. {Being Redesigned


CO2 Rocket Circles

A CO2 cartridge produces rotational motion. It is either attached to a model plain on a wire, or mounted to a freely rotating counterbalanced bar or platform.


Ball Bearing Propulsion Cart

A cart is propelled down a track by 2 1/2" ball bearings rolling down a chute attached to the cart. See the University of Minnesota website.


Wild Air Hose

Tie one end of a 3' rubber hose to a spring and turn on the air, then cut the string.


Ethanol Alcohol Rocket

A 5 gallon water jug is shot about 20' across the stage with a 3'-6' flame to show propulsion of a rocket using ethanol as fuel. This demo does have performance failure rate of about 10%.


Computer Plots of Rocket Motion - Data from a Smart-pulley

Atwood's machine with a funnel on one side is used to generate speed, position, and acceleration graphs. See AJP 75(5), 472.

1N30. Collisions in One Dimension


Demonstration Name




Two balls, five balls, six balls on bifilar suspension. For theoretical references, see AJP 49(8),761, AJP 50(11),977, [AJP 72(12), 1508], TPT 35(7), 411.


Bowling Ball Collision Balls

A large frame holds seven bowling balls on quadfilar supports.


Billiard Balls

Roll a ball down an incline into a trough with five other balls.


Billiard Balls

Duckpin balls slide on two taut parallel steel wires.


Collision Balls, 3:1

Two ball collisions of pendulums on bifilar supports include elastic, inelastic, and 3:1 mass ratio. The balls may be coated in wax to reduce elasticity. See Sutton M-127.


Time Reversal Invariance

The collisions of equal length pendulums of different mass are used to demonstrate time reversal invariance. It also works with three balls. See AJP 41(4), 574.


Impedance Match Collision Balls

First a large ball hits a small ball, then other various sized balls are interposed to maximize energy transfer. See AJP 36(1), 46.


Collision Balls Analysis

A simplified model of the collision balls that goes beyond conservation of energy and momentum but is still within the scope of an introductory course. See AJP 54(7),660.


Elastic and Inelastic Collisions

Air gliders have springs on one end and the post/clay on the other.


Air Track Collision Tricks

Place a meter stick on two carts to give equal velocities. After one hits the end bumper, you have equal and opposite velocities. If the two cars have the same mass, then the total momentum is zero and when the collide they will come to rest. See AJP 42(8),707.



A moving glider collides with a stationary one and sticks.



A moving glider collides with a stationary one, both having bumpers.


Air Track collisions of Cars of Unequal Mass

Unequal mass air gliders collide. For example, a small cart hits a big one elastically. The big one is placed so that after the collision both carts hit the ends simultaneously. The carts will again collide at the original place.


Inelastic Collisions with Clay

Mount a plunger on one air track car and a cylinder packed with modeling clay on the other.


Velocity of a Softball

A softball is thrown into a box (inelastic collision) and the velocity of the box is obtained from the recoil distance.


Slow Inelastic Collision

An unrolling thread slowly transfers momentum between air track gliders. See AJP 54(7),658.


The Bouncing Dart

A dart hits a block of wood with a thud (inelastic) but with the pointer removed (elastic) knocks the block over showing greater impulse associated with elastic collisions. See TPT 22(5), 302.


Ball - Pendulum Collisions

A small ball rolls down an incline and strikes a larger pendulum bob on either a putty covered side or a plain steel side.


Pendulum - Cart Collisions

Two pendulums of equal length are released simultaneously from the same height so as to strike low friction carts. The pendulum bobs are of equal mass, one of steel and the other of clay. Greater momentum transfer during the elastic collision is observed.


Elastic and Inelastic Model

Two carts collide with a wall. One cart stops dead due to masses at oscillating inside with different frequencies. See the University of Minnesota website.


Double Ball Drop

Hold a large super ball on top of a basketball and drop the two together. Application to "slingshot effect" of space probes on the grand tour.


Velocity Amplification in Collisions

The complete treatment: double object, double ball, multiple ball, analog computer circuit, linear and non-linear models. See AJP 39(6),656.


Modified Double Ball Drop

A double mass-spring collision on a guide rod allows more control than the double ball method. See AJP 58(7),696.


Double Ball Bounce with Air Gliders

Let two air gliders accelerate down 30 cm of track and measure the rebound as the mass of the lead glider is increased.


Colliding Cylinders

One cylinder slides down a track and collides with another on a horizontal track. Friction is factored in. See AJP 42(1),54.


Air Track Collision Photo

Record air track collisions with strobe photography.

1N40. Collisions in Two Dimensions


Demonstration Name



Pendulum vs Golf Ball

A framework allows a billiard ball pendulum to strike another on an adjustable tee.


Orthogonal Hammers

Identical hammers hung at right angles hit a ball.


Shooting Pool

Use a 3' x 5' pool table to show collision.


2 Ball Collisions on the Overhead

Ink coated balls roll down chutes onto a stage placed on the overhead projector. See TPT 2(6), 78.


Pinball Shooter

A ball shooting box with a soapy glass surface and plans for a ball shooter. See AJP 31(3), 197.


Photograph Golf Ball Collisions

Suspend two golf balls from a ring that mounts on the camera lens, which looks toward the floor, and do a time lapse photo of the collision after one is pulled to the side and released. See AJP 30(7), 530; AJP 29(9), 636


Air Table Collisions - Equal Mass

Collide two pucks of equal mass on an air table, one moving and one stationary, while varying the angle of impact between them.


Air Table Collisions - Unequal Mass

Collide two pucks of unequal mass on an air table, one moving and one stationary, while varying the angle of impact between them.


Two Air Pucks Collisions

Collide 2 air pucks on a table or floor


Lost Momentum

The air pucks are modified so the line of force during the collision passes through the center of mass. See AJP 56(5),473.


9-Ball Collision Array

Collisions with an array of three by three balls on the overhead projector.


Focusing Collisions

Balls are suspended from one string and spaced at a distance of 3r. Depending on the angle the collision is initiated, the collisions will either focus or defocus. See AJP 48(6),496.


Bouncing Ball Simulation

An analog computer (circuit given) shows the path of a bouncing ball on an oscilloscope. See AJP 37(10),1008.


Super Ball Bouncing

Analysis of the trajectory of a super ball from the floor to the underside of a table and back to the hand. See AJP 37(1),88.


Computer Collisions

A FORTRAN program for collisions on a Tektronix 4012 graphics terminal and Honeywell DPS8 computer. See AJP 52(7),619.



fw: Linear_Momentum (last edited 2013-07-22 15:40:10 by srnarf)