Solid Steel balls with diameter of one inch (about 25 millimeters) are used in mechanics and magnetism experiments. They are also used in construction of pendulums and demonstration of Newton laws.

For proving Hookes Law of Elasticity, i.e. that elongation of an object is directly proportional to the load applied and demonstrating the phenomenon of simple harmonic motion of a vibrating weight, potential energy etc. Consists of an adjustable mirrored scale 15cm long, graduated in millimeters, mounted on a support rod 30cm long fitted on a base. A hook attached to the rod supports a spring and indicator. Provided with a 50g brass hanger. Required slotted weights can be ordered separately.

Cam is a wheel that is not round, or it is a round wheel that turns around an axle that is not at the center of the wheel. Cam is used to change the rotational movement into the reciprocating movement.
The holes are about 2.6 mm (0.1 inches) in diameter, but you can enlarge the holes using a right size drill bit.
This set includes four cams in 4 different shapes: Round eccentric cam, small Pear-shaped cam, snail cam, and large pear-shaped cam.

Small gears with a 2.5mm hole. Holes can be enlarged. Use the existing hole as a pilot hole.