WorksheetsEfficiency of a Heat Engine
Total questions: 30
Worksheet time: 18mins
An engine is a device that changes _________ energy in fuel to __________ energy.
mechanical, chemical
chemical, mechanical
kinetic, chemical
chemical, kinetic
The bore in which a piston operates is the ________.
Block
Head
Cylinder
Valve train
The engine part that slides back in forth in a cylinder is the _____________.
Valve
Piston
Crankshaft
Camshaft
Which is the correct order of events in an engine?
Intake, Power, Compression, Exhaust
Intake, Power, Exhaust, Compression
Intake, Compression, Power, Exhaust
Intake, Exhaust, Power, Compression
In a four stroke engine, gasoline must be mixed with the correct amount of _____________.
Water
Oil
Carbon dioxide
Air
Diesel engines use glow plugs to _______ the compressed air, causing it to combust.
heat
cool
release
compress
A _________ is the full travel of the piston, in either direction.
revolution
turn
cycle
stroke
If the change in internal energy is positive, does the temperature of the system increase or decrease?
If an engine has a hot reservoir with a temperature of 980 K and cold reservoir of 673 K. Give the maximum efficiency of the engine rounded to the nearest tenth.
(a)
If a heat engine exhausts 360 J of energy after performing 180 J of work. How much energy was provided from the hot reservoir?
(a)
A gas in a closed container is heated with 10J of energy, causing the lid of the container to rise 2m with 3N of force. What is the total change in energy of the system?
(a)
What is heat engine?
It is a device that converts electrical energy into heat energy.
It is a device that converts thermal energy into chemical energy.
It is a device that converts thermal energy into mechanical energy.
It is a device that converts chemical energy into mechanical energy.
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.
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
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
One of your daily routines is to have a cup of hot coffee early in the
morning. You have to boil water using kettle. Why does whistling kettle
whistles?
a. Water boils.
The water increases its temperature.
When the water boils, it produces steam that makes the cover to move.
At extremely high temperature, water boils then changes its phase into
steam that causes vibration as it passes through a tone hole of the whistling
kettle.
Which of the following branch of natural science deals with heat and its
transformation to various forms of energy?
Heat
Heat Engine
Temperature
Thermodynamics
Heat can do work. A device called heat engine is used to make it possible.
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.
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.
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
No engine can transfer all the input heat energy into useful work. Some energy is transferred to the surroundings. Which thermodynamic law is this?
1st Law
2nd Law
A Carnot engine function between two reservoir between 527 0C and 127 0C . Calculate the carnot efficiency for the engine.
50 %
60 %
65 %
75 %
80 %
What is the efficiency of an engine?
The ratio of work done by the engine to the exhaust heat
The ratio of work done by the engine to the input heat
The ratio of input heat to exhaust heat
The ratio of exhaust heat to input heat
