This apparatus demonstrates the independence of horizontal and vertical velocities. It comprises a polished wooden block 200 mm long, which is pivoted an L-section metal launching bar 180 mm long. The bar is spring loaded and provided with a trigger catch. A small hole near each end of the bar serves to locate a 18 mm diameter steel ball. As and when the catch is released one ball drops vertically while the other is projected horizontally. The fact that the vertical velocities of both balls are the same at any instant, despite the fact that one has a large horizontal component, is shown by the fact that both hit the floor at the same instant.

The apparatus is supplied complete with a pair of steel balls of 18 mm diameter which is stored in a covered recess in the wooden body.

This is to demonstrate the principle of conservation of momentum and showing that momentum is a vector quantity having both magnitude and direction.

The apparatus comprises : A curved wooden runway 275 mm long and 65 mm high at its highest point, having a groove 8 mm wide down which a steel ball is rolled. An index mark at the top of the runway is provided so that the ball may be rolled from a constant height ensuring reproducibility of results. A metal plate 100 mm square is attached to its lower end which enables the apparatus to be fixed to the edge of a bench by a G-clamp. The plate also has a slot for the attachment of object sphere support. An object sphere support is an adjustable device which attaches to the mounting plate of the runway and will support a ball either exactly opposite the end of the runway for head on collision or slightly offset for oblique impact. Supplied with a plumb bob for making the plumb line and Two spheres (steel ball bearings 16 mm diameters).

A pair of these trolleys are used for investigation on momentum velocity, acceleration etc. Both the trolleys are identical and each consists of a two rectangular wooden blocks 300 mm long moving on three low friction wheels. The trolley is fitted with spring loaded impulse rod. Rod has three positions to provide different impulses which is triggered by a release pin, In the front of each trolley two holes are drilled and fitted with corks. With removable metal pins at each end to enable trolleys to be stacked or to provide anchoring points for accelerating cords.

(a) Trolleys with rubber wheels fitted with ball bearing
(b) Trolleys with plastic wheels fitted on bushes