Science glossary film: Centripetal force

The inward-pointing force that keeps an object moving on a circular path. Centripetal force always acts at a right angle to the direction of movement, keeping the object on a curved path. Here, the centripetal force is provided by the string. When the person lets go, there's no longer an inward force acting on the hammer, so it stops moving in a circle and moves in a straight line instead.

Centripetal force always acts at a right angle to the direction of movement, keeping the object on a curved path. Here, the centripetal force is provided by the string. When the person lets go, there's no longer an inward force acting on the hammer, so it stops moving in a circle and moves in a straight line instead.