Step-by-step explanation:
Efficiency can be calculated using the formula:
Efficiency = (useful energy output / total energy input) * 100
In this case, the useful energy output is 720J and the total energy input is 1200J.
Efficiency = (720J / 1200J) * 100
Efficiency = 0.6 * 100
Efficiency = 60%
So, the efficiency of the motor is 60%.