Question

A well insulated and perfectly sealed room is installed with 4 HP fan to circulate air for 1.5 hours. Determine the increase in internal energy of the air answer is 1.61 x10^7 J

Answer 1

"Increase in internal energy = energy consumed by fan " as the room is perfectly insulated and sealed.

energy consumed by fan = power x time
power of fan = 4HP = 4 x 745.7 W = 2982.8 W
time = 1.5 hours = 1.5 x 60 x 60 = 5400 s

 energy consumed by fan = 2982.8 x 5400 = 16107120 J = 1.61x10^7 J

Increase in internal energy is 1.61x10^7 J