Al Tobias (wat4y) - Office: Gibson S123 & Physics 218, (434) 924-0538
Demonstrations are cataloged according to PIRA Bibliography
PLEASE REQUEST DEMOS WELL IN ADVANCE
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.
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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.