Work and Energy
Objects Pulled and Lifted
Work is demonstrated by pulling and lifting various objects.
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- A metric scale
- A box of weights
- String with a ring attached to pull the box
- A suspended bowling ball
Various objects are moved through different distances. The work is then calculated and expressed in the appropriate units.
Bowling Ball
A bowling ball suspended as a pendulum is set to swing.
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- Suspended bowling ball
- A small stool
A suspended bowling ball is allowed to swing as a pendulum, illustrating energy conservation. The person demonstrating allows the ball to swing out and then back in while using his nose as the reference point for maximum energy.
Falling Balls
Balls are dropped and the respective rebound distances are measured.
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- Balls of different sizes and shapes
- A meter stick
Various objects are dropped from a measured height and allowed to rebound from a table. The rebound height is then measured and the lost energy is discussed. The energy imparted to the table is neglected.
Lift Weights
Heavy weights are lifted using simple machines.
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- A heavy lead brick
- A wooden plank fulcrum
- A scale
- A pulley system
Two simple machines (lever and chain hoist) are used to demonstrate that a given amount of work may be done either with a large force moved through a small distance, or a smaller force moved through a larger distance.
Loop-the-loop
A ball is allowed to move on a loop-the-loop track.
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- Loop-the-loop track
- Balls
A ball is allowed to roll down the ramp and loop around the track. The motion is then analyzed based on the fact that the sum of the gravitational potential energy and the kinetic energy remains constant. Friction is ignored, although it is not completely negligible for a thorough analysis.
WF Pendulum
A weight attached to a Wilberforce pendulum oscillates in different modes.
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- Wilberforce pendulum
Conservation of energy is demonstrated with the aid of the Wilberforce pendulum. Gravitational potential energy, elastic potential energy, kinetic energy of translation, and kinetic energy of rotation are each involved in this tuned pendulum.
Swinging Toy Lion
A toy lion suspended as a pendulum is raised and lowered.
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- A large size toy lion
- Ropes and ceiling support
This demonstration illustrates how it is possible for a child in a swing to increase the amplitude of swing by doing net work against gravity. The demonstrator alternately raises and lowers the toy lion in simulation of the children alternately raising and then lowering their center of gravity in such a way that net work is done over any given cycle or half-cycle. Music is added for interest.