## KL10 SUPER BALLS

Which ball bounces highest?

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Raise both stacks of balls along the cables

and drop them from the same height.

When the largest ball is uppermost, the balls will hardly bounce at all. When the smallest ball is uppermost, the stack of Super Balls sends the smallest ball bouncing metres high.

The law of conservation of momentum derives from the third law of motion, or the law of reciprocal actions. The sum of the momentums of the objects before they collide and after the collision remains unchanged. When the smallest ball is situated on top of larger balls and the stack of balls is dropped, the small ball bounces much higher than its original height. The momentum of the lowermost ball is transferred through the middle balls to the uppermost ball. When dropped, the larger balls have a greater momentum than the smaller balls, because they weigh more. When the smallest ball is the lowest in the stack, its momentum is not sufficient to lift the larger ball off the top of the Super Ball stack.

If skaters stand in a line on slippery ice and one collides with the end of the line, the momentum of the skater who caused the collision moves through the line and pushes the first skater away from the line. The momentum and energy remain constant throughout the collision.