A rotating space heater used 1,400 joules of energy while heating a room. Of that total, 896
joules produced thermal energy, 181 joules produced kinetic energy, 203 joules produced light
energy, and 120 joules produced sound energy. What is the space heater’s efficiency?
36%
156.25%
56.25%
64%
To find the efficiency of the space heater, we need to calculate the total useful energy produced (thermal energy) divided by the total energy input:
Efficiency = (useful energy output / total energy input) x 100%
Given:
Total energy input = 1400 J
Useful energy output (thermal energy) = 896 J
Efficiency = (896 J / 1400 J) x 100%
Efficiency = 0.64 x 100%
Efficiency = 64%
Therefore, the space heater's efficiency is 64%.