Quality one-piece injection molded hi-impact plastic carts. They have low friction ball bearing wheels, space for
carrying up to five ordinary bricks as test masses, and provision for being towed along a smooth surface with varied,
integrally related forces obtained by stretching special rubber bands. The apparatus is designed for experiments in
velocity, acceleration, impulse, momentum, and energy, and may be used together with the DC Recording Timer No.
TH-2204 or AC Recording Timer No. TH-1378 in any mechanics experiment involving straight-line motion.