Why does heat engine cannot be 100% efficient?

• Some of the steam cannot make the turbines to move.

• The energy converted to mechanical energy is not enough.

• It is because all heat is converted into work to perform its function.

• It is because part of the heat input is utilized for the mechanical work and

  some heat input cools down due to friction and for the cycle to happen.

Tags

NGSS.HS-PS3-4

Heat engine like in a geothermal power plant follows series of pattern in its operations. How will you arrange the following in correct sequence? I. Part of the heat is used to do mechanical work on an object. II. Condensed water is brought back to the Earth to repeat the cycle. III. Heat is supplied to the engine by an external source called hot reservoir. IV. Some of the heat decreases its temperature and condenses back to water.

• I, II, III, IV

• I, III, II, IV

• III, I, IV, II

• III, IV, I, II

Tags

NGSS.HS-PS3-4

If you will have a company business in the future using heat engines, why will you intentionally run the engine at a high operating temperature?

• A heat engine reduces the heat energy from a heat source.

• Heat engine depends primarily on the temperature difference.

• The lower is the temperature of the input heat, the greater is the energy

  for power production.

• The higher is the steam temperature driving the turbine, the higher is the

  efficiency of the power production

Tags

NGSS.HS-PS3-4

What is the primary function of a heat engine?

• A) To convert thermal energy into mechanical work.

• B) To transfer heat from a cooler reservoir to a warmer one without doing work.

• C) To decrease the entropy of a system to zero.

• D) To convert all absorbed heat into work without any losses.

Tags

NGSS.HS-PS3-4

Which of the following is a false statement about heat engine?

• Heat Engine converts thermal energy into mechanical energy.

• Heat engine utilizes all thermal energy into useful work due to its 100%

  efficiency.

• Heat engine may be classified into two major types: internal

  combustion engine and external combustion engine.

• Heat engine uses a working substance that cools and/or heats,

  compresses and/or expands like water in a steam engine.

Tags

NGSS.HS-PS3-4

What happens when heat is added to a system?

• The thermal energy will be wasted.

• The thermal energy will increase and can do work.

• The thermal energy will decrease and can do work.

• The thermal energy will increase the temperature of the environment.

Tags

NGSS.HS-PS3-4

Geothermal power plant is a way to harness the thermal energy coming

from the Earth’s interior and uses heat engine to generate electricity. Which

is not included in the processes that all heat engines follow?

• Some of the thermal energy from the input heat increases the

  temperature in the geothermal power plant.

• The rest of the thermal energy decreases temperature, condenses into

  water and goes back beneath the ground through injection well.

• Heat is added to the engine by a hot reservoir. The hot water produces

  steam that turns turbine which is connected to generator that generates

  electricity.

• Some of the thermal energy from the input heat is used to do useful

  work like turning the turbine connected to generator generating

  electricity

Tags

NGSS.HS-PS3-4

Teacher Cristel is showing flash cards showing examples of heat engines in

your Science class. She asked you to choose which does not belong to the

group. What are you going to pick?

• car

• refrigerator

• motorcycle

• thermal power generator

Tags

NGSS.HS-PS3-3

NGSS.HS-PS3-4

Which of the following branch of natural science deals with heat and its transformation to various forms of energy?

• Heat

• Heat Engine

• Temperature

• Thermodynamics

Tags

NGSS.HS-PS3-4

The heat energy coming out of the hot reservoir, Q H , into the system (engine) is 200 J. The energy that goes out of the system into the cold reservoir, Q C , is 150 J of waste heat. In joules, how much work was done by the system?

Tags

NGSS.HS-PS3-1