Matthew Lam, Charling Li, Jasjit Manpotra
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When a large ball is dropped, with a smaller one stacked on top of it, onto a hard surface the
smaller ball will often rise much higher than it would if it was dropped onto the same surface by itself, while the larger ball hardly bounces at all.
Our aim was to investigate this phenomenon and design a multiple-ball system, using up to 4 balls, that will reach the greatest elevation of the top
ball.
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PERPETUAL MOTION SQUAD
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Foam Balls
Nylon Monofilament
Retort Stand
Image source: Erlenmeyer Flasks
WD-40 Oil
Image source: wd-40.com
1 Kg Weight
Image source: Barr & Grosvenor Ltd
Known Data:The height the balls are dropped from are at 95 ± 2.5 cm.The masses of the four balls are:○ #1: 0.6 grams;○ #2: 1.2 grams;○ #3: 2.5 grams;○ #4: 4.0 grams.
Assumptions:Acceleration due to gravity is 9.8 m/s2.Air resistance is negligible.
PERPETUAL MOTION SQUADNote: In this presentation all units of measurement will be in centimetres.
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Before impact
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On impact
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Before impact
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6 Sets of 2 trials 4-Ball system (Total mass 8.2 grams, Ratio of masses 6:12:25:40) Height dropped from: 97.17 cm Height Reached: 77.86 cm
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1, 2 & 3-Ball system (Total mass 4.3 grams, Ratio of masses 6:12:25) Height dropped from: 94.95 cm Height Reached: 48.40 cm
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1 & 2 -Ball system (Total mass 1.8 grams, Ratio of masses 1:2) Height dropped from: 94.33 cm Height Reached: 28.47 cm
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Astroblaster simulation program http://www.egtecno.com/applets/177/astroblaster-balls
PERPETUAL MOTION SQUAD
PERPETUAL MOTION SQUADNote: For these calculations, the coefficient of restitution is assumed to be 1.