[Sci] Energy On The Move (Semester 2)

Question 1

Describe the transfer of heat energy by conduction.

Answer 1

Transfer of heat energy via conduction occurs when two objects are touching.

Question 2

Describe the transfer of heat energy by convection.

Answer 2

Transfer of heat energy via convection occurs in fluids via convection currents, when hot fluids rise up while cold fluids sink down.

Question 3

Describe the transfer of heat energy by radiation.

Answer 3

Transfer of heat energy via radiation occurs via electromagnetic radiation, and does not require a medium.

Question 4

Define the term ‘thermal conductor’.

Answer 4

any material that conducts heat

Question 5

Define the term ‘thermal insulator’.

Answer 5

a material of relatively low heat conductivity that shields a volume against loss of heat.

Question 6

Provide two examples of conductors.

Answer 6

carbon, copper

Question 7

Provide two examples of insulators

Answer 7

styrofoam, glass

Question 8

What is sound energy?

Answer 8

a form of energy associated with the vibration / disturbance of matter

Question 9

How is sound energy transferred?

Answer 9

Particle to particle collisions in the medium transmitting the sound wave.

Question 10

What are the variations of pressures in sound waves called?

Answer 10

Compressions and rarefactions

Question 11

Why do sound waves require a medium to propagate?

Answer 11

Sound waves occur when particles vibrate, so a medium is required which contains particles that can be vibrated to create the vibrations.

Question 12

What is a compression?

Answer 12

The areas of air where the particles are forced together

Question 13

What is a rarefaction?

Answer 13

The areas of air where the particles are spaced further apart.

Question 14

Explain the difference between a compression and a rarefaction.

Answer 14

• Compression: areas of air where particles are forced together
• Rarefaction: areas of air where particles are spaced further apart

Question 15

What is a sound wave?

Answer 15

a wave of compression and rarefaction, by which sound is propagated in an elastic medium such as air.

Question 16

What’s an alternate name for a sound wave?

Answer 16

longitudinal wave

Question 17

Why can sound waves also be called longitudinal waves?

Answer 17

the air particles vibrate parallel to the direction of travel of the wave.

Question 18

Why can’t sound travel through empty space?

Answer 18

• Sound is defined as the vibration of matter.

- Empty space / vacuum contains no matter, therefore sound cannot occur.

Question 19

What is a transverse wave?

Answer 19

A wave in which the medium vibrates at right angles to the direction of its propagation

Question 20

What is an example of a transverse wave?

Answer 20

Light

Question 21

What does EM field stand for?

Answer 21

Electromagnetic field

Question 22

What kind of medium is an EM field?

Answer 22

Nonphysical

Question 23

Why doesn’t light require a medium through which to travel?

Answer 23

• Light is an excitation of the EM field: an EM wave.
• The EM field permeates everything in space, and in its ground state always exists.
• The excitations of the field can thus propagate through matter and a vacuum.

Question 24

What is the wave equation?

Answer 24

v = f × λ (lambda)

Question 25

What can the wave equation be used for?

Answer 25

the speed, frequency or wavelength of a wave

Question 26

In the wave equation, what does v stand for?

Answer 26

speed of the wave (m/s)

Question 27

In the wave equation, what does f stand for?

Answer 27

frequency of the wave (Hz)

Question 28

In the wave equation, what does λ stand for?

Answer 28

wavelength of the wave (m)