Al Tobias (wat4y) - Office: Gibson S123 & Physics 218, (434) 924-0538

# Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography

Due to Physics Building renovations, the lead time to set up demo requests has increased due to the need to transport equipment across campus. Please be kind and let me know well ahead of time what you need.

 Choose a Topic or Enter a keyword to search: I cannot find what I want! You have selected the following Demos: None Selected

Choose a subtopic:
Measurement
Motion In One Dimension
Motion In Two Dimensions
Newton's First Law
Newton's Second Law
Newton's Third Law
Statics Of Rigid Bodies
Applications Of Newton's Laws
Gravity
Work and Energy
Momentum
Egg in a Sheet
Reaction Cars
video  - Ballistics on Air Track
Ballistic Pendulum
Fire Extinguisher Rocket Cart
Water Rocket
Rocket Tricycle
Methanol Rocket (Explode a Milk Jug)
Match Rocket
video  - 2-Liter Bottle Rocket
video  - Hovercraft
video  - Air Track Collisions
video  - Battering Ram Collisions
Gauss Gun - Elastic and Inelastic Collisions
video  - Double Ball Bounce
video  - Air Table Collisions
Rotational Motion
Properties of Matter

### Reaction Cars

#### Purpose:

To illustrate conservation of momentum and Newton's Laws.

#### Procedure:

This can be done two ways:

1. PASCO TIMERS: Set up cars in the middle of the track with two photogates on either side set to measure the travel time between gates and calculate their velocities after release. Use PASCO Capstone file "Reaction_Cars_with_Speed_Measurement.cap".
Or, use only one photogate on either side of track, each measuring instantaneous velocity using width of 1cm flag on each car. Use PASCO Capstone file "Reaction_Cars_with_Velocity_Measurement.cap".

2. PATH LENGTH: Release the cars at different points until both cars reach the end of the track simultaneously. In either case the cars' mass ratio can be shown or the cars can be weighed and their momentum calculated.

#### Hints:

For example, if one uses the carts shown in the image below, the mass ratio is 3 to 1. The larger cart has mass of 576 grams, the smaller cart has mass of 192 grams. If large cart is on the left, small cart on the right, place left edge of large cart on 50 cm mark, right edge of small cart on 92 cm mark, upon release of spring (expands about 8 cm), carts will hit edges of track simultaneously showing the small cart traveled three times the velocity compared to large cart.

#### Equipment:

• Timer
• Air car spring launcher
• Gliders w/ spring attachment