You exercise on a stationary bike and your internal energy decreases by 175 cal. If you did 33 cal of work on the pedals of the bike, how much heat flowed into or out of your system?

Question

Quizplus · Accepted Answer

According to the first law of thermodynamics, the change in internal energy (ΔU) is equal to the heat added to the system (Q) minus the work done by the system (W). Here, ΔU = -175 cal and W = 33 cal. So, Q = ΔU + W = -175 cal + 33 cal = -142 cal, meaning 142 cal flows out of the system.

You Exercise on a Stationary Bike and Your Internal Energy