A machine uses 1000 j of electric energy to raise a heavy mass, increasing its potential energy by 300 j. what is the efficiency of this process? yahoo

The efficiency is obtained or calculated by dividing the work successfully done by the machine by the total amount of energy spent to perform the work. Then, multiply the obtained ratio by 100%. From the given,

efficiency = (300 J / 1000J) x 100% = 30%

Thus, the machine is only 30% efficient.