This is another demonstration of a basic law of motion that students may not quite believe at first viewing. The car carries a vertically directed spring-loaded barrel. Drop a steel ball down the barrel, cock the spring and give the car a push. The ball is ejected but coincidentally falls back into the barrel while the car continues to roll. The spring offers two different tensions. The car is our low-friction Hall’s Carriage. Complete with 25mm steel ball, trigger pin, pin cord and instructions.
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