In the first law of thermodynamics, ΔE=Q−W , what does ΔE stand for? the change in the internal energy of the system

the work done by the piston

the heat added to the system

the internal energy of the system

An ideal otto cycle has a compression ratio of 10.5, takes in air at 90 kpa and 40°c, and is repeated 2500 times per minute. using constant specific heats at room temperature, determine the thermal efficiency of this cycle and the rate of heat input if the cycle is to produce 90 kw of power.