A very large cable spool (or smaller version) is made to roll in either direction or slide, depending on the angle of pull; action of a torque.
What it shows:
Depending upon the angle of applied force, a yo-yo can be made to roll forwards, backwards or simply slide without rotating.
How it works:
The effect of force angle is illustrated in figure 1; (a) and (b) are the extreme cases. For (a), pulling the string vertically creates a torque r1F rotating the yo-yo counter-clockwise. Pulling the string horizontally as in (b) creates a...
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