This simple device comprising a large track is quite useful in demonstrating the conversion of potential energy into linear and rotational kinetic energy and again back into potential energy. The V shaped metal track has unequal arms, but their highest points at equal height, so as to form two adjacent inclined tracks of dissimilar lengths (hence unequal angle of inclinations) and is supported on 1.5m long wooden base. The concept is beautifully illustrated when balls of different materials, (two metal and one plastic included), are rolled down the track from either end