Answer:
The rate of heat supply is 8.901 horse-power.
Explanation:
From Thermodynamics energy efficiency of the electric car ([tex]\eta[/tex]), no unit, is the ratio of translational mechanical power ([tex]\dot E_{out}[/tex]), measured in horse power, to electric power ([tex]\dot E_{in}[/tex]), measured in horse-power. The rate of heat supply ([tex]\dot E_{l}[/tex]), measured in horse-power, by the motor to the engine compartment at full load is difference between electric energy and translational mechanical energy. That is:
[tex]\eta = \frac{\dot E_{out}}{\dot E_{in}}[/tex] (1)
[tex]\dot E_{l} = \dot E_{in}-\dot E_{out}[/tex] (2)
[tex]\dot E_{l} = \left(\frac{1}{\eta}-1\right)\cdot \dot E_{out}[/tex] (3)
If we know that [tex]\eta = 0.91[/tex] and [tex]\dot E_{out} = 90\,hp[/tex], then rate of heat supply is:
[tex]\dot E_{l} = \left(\frac{1}{0.91}-1 \right)\cdot (90\,hp)[/tex]
[tex]\dot E_{l} = 8.901\,hp[/tex]
The rate of heat supply is 8.901 horse-power.
