Question

While riding his bicycle, Jans does 7.5 E7 J of work and gives off 4.3 E7 J of heat. What is the change in Jan's internal energy?

+ 3.2 E 7 J
−3.2 E 7 J
−11.8 E 7 J
+11.8 E 7 J

Answer 1

-11.8 E 7 J

Step-by-step explanation:

the first law od thermodynamics: dU=dQ-W, where dQ is heat added to the system (Jan), and W is work done by the system (Jan). Since the system is giving heat, dQ is negative, so: dU=-4.3E7 J - 7.4E7 J = -11.8 E7 J.