Two electric saws, P and Q, each operate for 20 s while cutting timber. Saw P does 3.0 kJ of useful work and saw Q does 2.0 kJ of useful work.
Which statement correctly compares the useful power outputs of the saws?
P has the greater useful power because it does more useful work in the same time.
P and Q have the same useful power because they operate for the same time.
Q has the greater useful power because it wastes less energy while cutting.
Their useful powers cannot be compared without knowing the total energy supplied.