Rocky's base metabolic rate is 100 W (when not exercising). He weighs 80 kg. This morning, he climbed stairs 25-cm high at the rate of 140 steps per minute for 30 minutes on a Stairmaster. Assume potential energy is expended climbing up and 20% of that energy is used climbing down.
a. How much energy did he burn (in J and in kWh)?
b. What was his total average power (in W) during the exercise?