The power of an engine is often determined by experiment with the aid of a device called a brake dynamometer consisting of two blocks pressing against the shaft of the motor. To one of the blocks is attached a lever from which weights are suspended (Fig.). The load is chosen so that it equals the frictional force, the lever arm remaining in a horizontal position. Find the power of the motor if the shaft rotates at 60 rev/min, the length / of the lever measured from the centre of the shaft is 1 m, and a weight Q of 50 kg-wt balances the lever. Neglect the weight of the lever.
