Labs / Physics
Ball on a String
A ball whirls in a circle because the string keeps pulling it inward — that inward pull is the centripetal force, F = mv²/r. Change the speed, radius, and mass, then cut the string and watch the ball shoot off along the tangent, not outward.
Fc 9.0 NTension 9.0 NPeriod 1.57 s
What to try
- When you cut the string, does the ball fly straight outward or off to the side? Why that direction?
- Double the speed. Does the required force double, or grow faster than that?
- Widen the radius while keeping the speed fixed — does the string need more tension or less?
- If you were swinging a real bucket, would a heavier ball be harder to keep in the circle?
- What combination of speed and radius gives the shortest period — the fastest lap around the circle?