Energy and Heat

Question 1

How are energy and work related to each other?

Answer 1

Energy is the ability to do work so they are equivalent but not the same. Work is kind of an applied energy. Energy can tell you how much work can be done.

Question 2

What is the difference between potential and kinetic energy? Give an example.

Answer 2

Potential energy is stored energy. (An object held above the ground)
Kinetic energy is flowing energy. (A falling object)

Question 3

Will doubling the speed of an object double it’s kinetic energy?

Answer 3

No. Take a 1kg object that is traveling at 2m/s.
Ek=1/2mv^2 which would be Ek=1/212^2 which equals 2J
If you double the speed Ek=1/214^2 which equals 8J.
You would need lees than double the velocity to double the energy because the relationship is exponential.

Question 4

Give an example of elastic potential energy.

Answer 4

Bouncing balls, rubber bands, springs, etc.

Question 5

A 1kg weight is resting 2m above the ground. What is it’s potential energy?

Answer 5

Ep=mgd Ep=19.82 Ep=19.6

Question 6

Give an example of thermal energy sources or machines that use thermal energy.

Answer 6

Hot sandy beach, cold snow, ovens, furnaces, air conditioner.

Question 7

Give some examples of chemical energy sources or machines that use chemical energy.

Answer 7

Gasoline, Natural gas, Batteries, Food

Question 8

What happens to the particles that make up an object when the object heats up?

Answer 8

The particles begin to move more rapidly. A change in the particles kinetic and potential energy.

Question 9

What is the energy conversion that a toaster makes?

Answer 9

Electricity to Heat (Light)

Question 10

What energy conversion does a plant make?

Answer 10

Solar or electromagnetic to chemical.

Question 11

What is the relationship shown in the equation E=mc^2

Answer 11

The relationship between light, mass, and energy. Show that a certain amount of mass can be converted to energy.

Question 12

Why do we continue to use fossil fuels?

Answer 12

They a relatively inexpensive, the infrastructure is already there, it is what we are used to,

Question 13

What is the commonly used metric unit for temperature?

Answer 13

Degree Celsius, a Kelvin which is based on absolute zero is commonly used in science.

Question 14

What causes heat to transfer from one object to another?

Answer 14

A temperature difference between two objects.

Question 15

What happens to the potential energy of an object as that object loses temperature.

Answer 15

The potential energy goes down.

As heat is transferred the object loses energy.

Question 16

What factors determine an objects thermal energy. (3)

Answer 16

Mass, Phase, Temperature

Question 17

If you reach your hand into a hot stove, your hand heats up because of…

Answer 17

Convection, the heat is transferred through the air in the stove.

Question 18

If you touch the rack in a hot stove your hand heats up because of…

Answer 18

Conduction, conduction is heat transfer through direct contact and is more efficient than convection.

Question 19

How does energy from the sun reach the Earth?

Answer 19

Radiation, radiation is energy transfer through electromagnetic waves. Space is mostly a vacuum so conduction and convection simply do not work.

Question 20

Name an item that conducts heat well.

Answer 20

Any metal is a good option.

Question 21

What need to be done to make energy flow from colder object to hotter objects?

Answer 21

Work.

The third law of thermodynamics states this. (Things go from order to disorder.

Question 22

What does conservation of energy mean?

Answer 22

Energy cannot be created or destroyed it only changes form. This is the first law of thermodynamics.

Question 23

What does the third law of thermodynamics state?

Answer 23

Absolute zero cannot be reached.

Question 24

How is a steam engine different from the engine in your car. In terms of how energy is converted.

Answer 24

A steam engine is an external combustion engine that burns the fuel outside of the engine, generating steam which expands air, which pushes a piston.
A car engine is internal combustion where the fuel is burned inside the engine. The burning of the fuel causes a change in volume.

Question 25

What are the main components of a forced air heating system?

Answer 25

A furnace to convert electricity of fuel into heat, and a blower to circulate warmed air throughout the structure.

Question 26

What is the name of the fluid that is in your refrigerator?

Answer 26

Refrigerant, a refrigerant is a substance that vaporizes and condenses easily allowing it to transfer heat more effectively.