Boxi Learn › Physics › Stage 4 · Systems and Argument
Which way does the ball fly when the string breaks?
PHY-1 A force changes motion, it does not keep it goingPHY-5 Motion depends on who is watchingX-1 Guess, then checkX-3 Look from another side
What many people think
A centrifugal force flings the ball outward, or it keeps curving after the string breaks.
The idea
Going round a circle needs a force pointing to the centre; take it away and the ball flies off in a straight line along the tangent, not outward and not in a curve.
Explain it
A friend says the ball flies straight outward when the string snaps, because centrifugal force throws it. Explain where it really goes and why, and why it still ends up farther from the pin.
Try at home
Cut a slice out of the rim of a paper plate. Lay it flat and roll a marble fast round the inside of the rim. Where does the marble go when it reaches the gap? Mark the path with flour or a ruler.