A student observes four different situations in which objects move in circular paths…
PHYSICS · Multi-part · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics
Problem
A student observes four different situations in which objects move in circular paths with constant speed. In each case the student wishes to know what real physical interaction supplies the necessary inward (centripetal) force.
(a) (i) A stone of mass 0.20kg is whirled at constant speed on a horizontal frictionless tabletop, being tied to the centre by a light string.
(b) (ii) The Moon revolves around the Earth in an almost circular orbit of radius 3.84×105km.
(c) (iii) A car negotiates a level circular track of radius 40m without skidding.
(d) (iv) Water contained in a bucket is swung in a vertical circle of radius 0.8m at such a speed that it does not spill even when the bucket is upside down at the highest point.
(e) For each case:
(a) Name the real force or forces that provide the required centripetal force.
(b) Explain briefly how the identified force(s) act toward the centre of the circle.
(c) State whether any of the identified forces (if more than one) only partly contribute to the centripetal force, giving reason.