Heat Engines Practice

Front

What is the thermal efficiency range of a petrol engine?

Back

20% - 30%

Front

If 750J of heat is added to an isolated gas and it does 230J of work, what is the change in thermal energy?

Back

520 J

Front

A heat engine does 220J of work when receiving 600J of heat. How much energy is emitted through the exhaust?

Back

380 J

Front

In energy transformations, what form does 'wasted energy' usually take?

Back

heat

Front

How efficient is a washing machine that uses 250J of electrical energy to produce 125J of useful energy?

Back

50%

Front

Define thermal efficiency.

Back

Thermal efficiency is the ratio of useful work output to the total heat input, expressed as a percentage.

Front

What is the formula for calculating thermal efficiency?

Back

Thermal Efficiency (%) = (Useful Work Output / Total Heat Input) x 100

Front

What is the significance of 'wasted energy' in heat engines?

Back

Wasted energy indicates energy that is not converted into useful work, often lost as heat.

Front

Explain the first law of thermodynamics in the context of heat engines.

Back

The first law states that energy cannot be created or destroyed, only transformed from one form to another.

Front

What is the role of exhaust in a heat engine?

Back

Exhaust is the energy that is not converted into work and is expelled from the engine.