Why is a heat engine never 100% efficient ?

What is heat engine ?

Why can't the efficiency of a heat engine ever be 100 % ?

To maintain a rotor at a uniform angular speed of 200 rad s-1, an engine needs to transmit a torque of 180 N m. What is the power required by the engine ? (Note: uniform angular velocity in the absence of friction implies zero torque. In practice, applied torque is needed to counter frictional torque). Assume that the engine is 100% efficient.

Even Carnot engine cannot give 100% efficiency because we cannot

An ideal Carnot heat engine with an efficiency of 30% . It absorbs heat from a hot reservoir at 727^(@)C . The temperature of the cold reservoir is

A Carnot engine, whose efficiency is 40% , takes in heat from a source maintained at a temperature of 500K. It is desired to have an engine of efficiency 60% . Then, the intake temperature for the same exhaust (sink) temperature must be:

Under which ideal condition, the efficiency of a carnot engine become 100% ?

The temperature of the sink of a carnot engine is 300 K and its efficiency is 40 %. Find the decrease in temperature of the sink required to increase the efficiency of the engine to 50% keeping temperature of the source to be constant.

The efficiency of a heat engine is defined as the ratio of the mechanical work done by the engine in one cycle to the heat absorbed from the high temperature source . eta = (W)/(Q_(1)) = (Q_(1) - Q_(2))/(Q_(1)) Cornot devised an ideal engine which is based on a reversible cycle of four operations in succession: isothermal expansion , adiabatic expansion. isothermal compression and adiabatic compression. For carnot cycle (Q_(1))/(T_(1)) = (Q_(2))/(T_(2)) . Thus eta = (Q_(1) - Q_(2))/(Q_(1)) = (T_(1) - T_(2))/(T_(1)) According to carnot theorem "No irreversible engine can have efficiency greater than carnot reversible engine working between same hot and cold reservoirs". An inventor claims to have developed an engine working between 600K and 300K capable of having an efficiency of 52% , then -