What it shows:

An object finds itself heavier and pinned against the wall of a spinning cylinder; the principle behind fairground Barrel of Fun rides and centrifuges.

How it works:

The object in such a ride experiences two forces, that of its weight and the centripetal force exerted by the barrel wall; the vector addition of these forces giving the apparent increase in weight (figure 1 ) The reaction force of the object also presses it against the wall; the increased friction force preventing it from sliding down.

The barrel in our demo is a 45cm...

What it shows:

An object rolling down a hill acquires both translational and rotational kinetic energy. One must take the rotational kinetic energy into account when calculating the object's velocity at the bottom of the hill

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A very large cable spool (or smaller version) is made to roll in either direction or slide, depending on the angle of pull; action of a torque.

What it shows:

Depending upon the angle of applied force, a yo-yo can be made to roll forwards, backwards or simply slide without rotating.

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Lecturer rotates on turntable whilst holding two dumbbells.

What it shows:

Angular momentum, the product of a body's moment of inertia and angular velocity, is always conserved. A reduction in moment of inertia will result in a proportional rise in angular velocity.

How it works:

A volunteer holds the other two dumbbells ¹ in each hand and stands upon a rotating platform. ² With arms outstretched and a little push they begin to rotate at a certain angular velocity. By pulling in their arms to their chest, the moment of inertia is...

A pendulum is allowed to "crash" into a bar, dramatically altering its motion, but energy is conserved as is evidenced by the return swing.

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Requiring little or no skill and the aid of a carpenter's square, one shot sinks two balls into the pockets.

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What it shows:

Using conservation of energy, calculate the height from which Barney must jump so that his head just barely kisses the floor at the bottom of his bungee cord jump. Then verify by experiment. Oops ... hate when that happens! It turns out that it's not so simple and there are important details that must be taken into account.

How it works:

Barney (the friendly pink dinosaur) is "sandbagged" (with a 5 kg weight, duct-taped around his waist) and suspended from the sky-hook by a 3.1 meter-long (unstretched) spring. The spring constant has been measured...

Use conservation of energy to predict the height the arrow will reach.

What it shows:

When the string of a bow and arrow is pulled from equilibrium, the elastic potential energy in the bow is converted to kinetic energy of the arrow when...

Faith in the conservation of energy is tested by taking the demonstrator's nose to task.

What it shows:

The principle of conservation of energy ensures that a pendulum released at a particular amplitude will not exceed that amplitude on the return swing. A lecturer's faith in their subject is put to the test using a 50lb (22.7kg) iron ball.

How it works:

Technique is very important here. The best method to employ is to stand with your back against the blackboard with your head also touching the board. This ensures that you don't lean forward after release....

A falling weight propels a car forward.

What it shows:

Gravitational potential energy can be converted into mechanical kinetic energy.

How it works:

A Gravicar is a vehicle powered by gravitational potential energy that it stores in...

Single seat CO₂ powered rocket cars.

Photo by Rose Lincoln

Radio controlled car moves one way while road moves the other.

What it shows:

We tell our students that, when a car drives down the road, the road and the Earth move in the opposite direction, albeit imperceptibly. This demonstration is a realization of that concept, made possible (and perceptible) by the fact that the road is not attached to the Earth.

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What it shows:

A straightforward demonstration of Newton's 3rd law, that forces are interactions and thus come in pairs.

How it works:

Two people, each sitting (cross-legged) on their own board, position themselves in the center of the track facing each other. Upon pushing against each other with their hands, they glide apart down the length of the track. Repeat this with one person turned around — the other person pushes on his/her back instead of pushing against each other with their hands. The ensuing motion down the track is exactly the same as before.

Calculation of gravitational constant, with accompanying apparatus model.

What it shows

The gravitational attraction between lead spheres. The data from the demonstration can also be used to calculate the universal gravitational constant G.

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Falling in an evacuated tube at the same rate.

What it shows:

In the absence of air resistance all bodies, regardless of size or weight, fall with the same acceleration at the same point above the Earth. Here a feather and a dime (see Comments) fall under the influence of gravity in an environment where there is no air to mess things up.

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