“Suction” pads
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A suction pad on the end of an ‘arrow’.
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A ball which sticks to any smooth surface when thrown at it.
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A somersaulting frog. When the suction pad releases, the frog does a neat back flip.
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A ‘bug’ which leaps into the air. When the suction pad releases, the bug leaps high into the air.
The Physics.
The rubber or plastic suction* pad is the basis of many toys and novelties.
By pressing the cup shaped disc onto a smooth surface, air is excluded, and when the external pressure is released, atmospheric pressure continues to hold the disc onto the surface. Thus it remains until leakage of air past the edge destroys the partial vacuum and the disc is released. How long this takes depends on the effectiveness of the seal around the edge. A little moisture applied to the pad makes it stick rather longer.
The leaping bug also demonstrates energy conversion in a fairly dramatic way.
The elastic potential energy stored in the spring is converted into kinetic energy which in turn is transformed into gravitational potential energy as it rises to a height of a foot or two.
*Note; Strictly speaking there is no such thing as ‘suction’, only a difference of pressure. But try telling that to small children!