If one-third of that energy goes into engine heat and other forms of internal energy, with the rest going into engine power, how much torque will that engine develop if you rev it at 2100 rpm? min?
2(10800)/3 = 7200J
Power, P, is energy per unit time:
P=7200/60=120W
The torque is given by
T = P/2πf where f is the frequency (revolutions per second)
T = 120/2π(2100/60) = 0.546 N m