Brachistochrone
Three balls race down different paths (straight, parabolic, and cycloid) to show that the shortest distance is not the fastest route. The cycloid wins because its steep initial drop builds …
Motion in Two Dimensions Topic
Safety
Center of Mass: Rubber Cork Bolas
Two unequal rubber stoppers connected by rope are tossed through a UV beam in a dark room. The stoppers trace complex curves, but a fluorescent tape marking the center of …
Barycenter: Pluto and Charon
Scale model of the Pluto-Charon system demonstrates that both bodies in a binary system orbit their common center of mass (barycenter). Because Charon is so massive relative to Pluto, the …
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.
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 …
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 …
Safety
Flattening Earth
A flexible hoop on a hand-cranked centrifugal machine flattens into an oblate shape as rotation speed increases, modeling Earth's equatorial bulge. Students see how centrifugal effects deform rotating bodies and …
Safety
Water Parabola
A water-filled glass cylinder spun on a centrifugal machine produces a parabolic free surface. Students see that the equilibrium shape results from the balance of gravitational and centrifugal forces in …
Safety
Rotating Accelerometer
Provides cognitive dissonance for students who expect all objects in a rotating system to be flung outward. An inverted water-filled flask with a fishing float is spun on a rotating …
Marble in Open Ring
A marble rolling inside a 3/4 ring exits through the gap in a straight line tangent to the circle, demonstrating Newton's First Law. Directly addresses the common misconception that objects …
Trajectory of Swinging Ball
Demonstrates that objects in circular motion travel in a straight line tangent to the circle when released, directly illustrating Newton's First Law. Corrects the common misconception that released objects fly …
Juggling Balls
Lightweight, non-bouncing balls for demonstrating 1D and 2D motion with little risk of damage. Can be thrown from rest or from a moving cart to show projectile motion and relative …
Safety
Cart with Cannon
A ball launched vertically from a moving cart follows a parabolic arc in the lab frame but travels straight up and down in the cart's frame — and lands back …
Safety
Basketball Cannon Cart
A basketball fired vertically from a moving cart lands back in the cannon, demonstrating that projectile trajectory depends on the observer's reference frame. From the cart's frame the ball goes …