Central Forces Concept

Demonstrations in Central Forces

Cast-iron A-frame centrifugal machine with large hand-crank wheel at bottom, belt drive to small pulley at top of the frame, yellow warning label on base
Safety

Circular Motion Apparatus

A hand-cranked centrifugal machine with a 5-to-1 gear ratio demonstrates gear ratios and angular velocity multiplication. One turn of the crank produces just over five revolutions of the output spindle.
Tennis ball attached to white cotton cord with knots at two positions and a loop handle at the end
Safety

Ball on String

Demonstrates centripetal force and circular motion by swinging a ball on a string in horizontal and vertical planes. Students observe how tension depends on speed, radius, and position in the …
Tennis ball on white string hanging vertically from a tall rod bench-clamped to a green demo table, chalkboard behind

Conical Pendulum - Tetherball

A ball on a string traces a conical pendulum path, providing a clear visual for discussing central forces and circular motion. Students analyze how the horizontal component of tension provides …
Large inverted wine glass over an orange superball on a white surface against a dark background

Ball in Inverted Wine Glass

A ball orbiting inside an inverted wine glass stays up instead of falling out. Students analyze the force balance — normal force from the curved surface provides centripetal acceleration while …
White plastic bucket with wire handle and rope threaded through it, looped around a person's wrist and hand for secure grip
Safety

Whirling Bucket

A bucket of water swung in a vertical circle stays dry — even when inverted — because the centripetal acceleration exceeds at the top. Illustrates circular motion dynamics and addresses …
Hand holding a wire coat hanger bent into a diamond shape, with a penny balanced on the curved hook at the bottom

Penny and Coat Hanger

A penny balanced on the hook of an elongated coat hanger stays in place when the hanger is swung in a vertical circle around your finger. Students see that the …
Metal hoop mounted vertically on a brass spindle attached to a black hand-cranked centrifugal machine, with a small carabiner hanging at the bottom of the hoop
Safety

Ring on Spinning Hoop

A carabiner slides freely on a hoop mounted on a hand-cranked centrifugal machine. As rotation speed increases, the carabiner rises up the side of the hoop, reaching an equilibrium angle …