A jogger's internal energy changes because he performs 6.80 105 J of work and gives off 4.9 105 J of heat. However, to cause the same change in his internal energy while walking, he must do 8.10 105 J of work. Determine the magnitude of the heat given off while walking.

Question

A jogger's internal energy changes because he performs 6.80  105 J of work and gives off 4.9  105 J of heat. However, to cause the same change in his internal energy while walking, he must do 8.10  105 J of work. Determine the magnitude of the heat given off while walking.
 J

Damon · Answer

decrease in U = work done + heat given off =(6.8 +4.9)*10^5 = 11.7 * 10^5 J then 11.7*10^5 = 8.1*10^5 + heat given off heat given off = (11.7-8.1)10^5 = 3.6*10^5 J