Thermal Physics

Question 1

Good conductor (bad insulator) examples

Answer 1

metals

Question 2

Solid –> Liquid

Answer 2

Melting

Question 3

Liquid–>Solid

Answer 3

Freezing

Question 4

Liquid –> Gas

Answer 4

Evaporation/Boiling

Question 5

Gas –>Liquid

Answer 5

Condensation

Question 6

What is Brownian Motion

Answer 6

Random motions of particles in fluids (liquid or gases) and is caused by collisions with smaller, faster-moving particles

Question 7

How do Temperature and motion of particles correlate?

Answer 7

In a solid- Particles vibrate about a fixed point causing the temperature to rise

Question 8

How do Pressure and motion of particles correlate? [3]

Answer 8

1. Gases have particles moving randomly at high speeds
2. Each colission with wall changes it’s momentum and creates a force
3. Average Pressure remains constant at cconstant pressure
4. Increases if temperature raises

Question 9

What happens (Gas) when the volume is changed at constant temperature

Answer 9

1. Increased volume, lower pressure- more particles per unit volume
2. Decreased volume- higher pressure

Question 10

Thermal expansion in the three states of Matter [3]

Answer 10

Solids/Liquid- particles vibrate more pushing them apart slightly
Gas: Increased particle speed- causes container to expand

Question 11

What are Bimetallic strips

Answer 11

Made from metals with different expansion rates

Question 12

What are Bimetallic strips used in [2]

Answer 12

1. Fire alarms- bends to complete an electrical circuit when exposed to heat- triggers alarms
2. Lid removal- Expanding metal lids with hot water loosens them from glass jars- easier to open

Question 13

MP and BP of water [2]

Answer 13

MP- 0 C
BP- 100C

Question 14

Condensation in terms of Particle

Answer 14

gas particles losing potential energy to their surroundings- return to liquid state

Question 15

Solidification in terms of Particle

Answer 15

transfer ofpotential energy from particles to surroudings- return to solid state

Question 16

Describe melting and boiling in terms of energy

Answer 16

Energy is given to a solid/liquid enough for them to overcome their intermolecular forces to become a liquid/gas

Question 17

What are the three things that Increase the rate of evaporation [3]

Answer 17

1. Higher Temperature
2. Larger surface area
3. Wind/Draught

Question 18

What does evaporation do to the temperature

Answer 18

Eergy is tranferred to the surroundings from liquid- cooling it

Question 19

Difference between Evaporation and Boiling [4]

Answer 19

1. B happens at a certain temp, E happens any temp under BP
2. B requires cetain amont of energy + heat, E is only the energetic particles escaping
3. B is faster, E is slower
4. B happens throughout the whole liquid, E happens only at the surface

Question 20

Define Conduction

Answer 20

heat transfer through matter from hot to cold- without moving matter

Question 21

Good insulator (bad conductor) examples

Answer 21

plastic
glass
wood

Question 22

Thermal conduction in non-metals

Answer 22

The heat causes atoms in the lattice to vibrate faster. These vibrations spread through the material cause the particles to all vibrate, and transferring the heat.

Question 23

Thermal Conduction in metals

Answer 23

Delocalized electrons carry heat energy by moving faster when heated, transferring energy throughout the metal.

Question 24

What is convection

Answer 24

process of heat transfer in fluids (liquids and gases)
- warmer particles (less dense) rise
- cooler particles (more dense) sink
creates a circular motion

Question 25

Thermal Radiation

Answer 25

Thermal radiation transfers energy without needing a medium - happens through infrared radiation

Question 26

How does surface color affect thermal radiation?

Answer 26

Black surfaces- absorbs and emits more thermal radiation than white surfaces White surfaces- reflect more thermal radiation and absorb less than black surfaces

Question 27

How does texture affect thermal radiation?

Answer 27

Dull surfaces- absorbs and emits more thermal radiation Shiny surfaces- reflect more and absorb less thermal radiation

Question 28

What controls the temperature of the Earth

Answer 28

Radiation absorbed and emmitted by the Earth