thermal physics

Question 1

property of solid

Answer 1

Fixed shape – keeps its shape because particles are tightly packed.

Fixed volume – does not change size easily.

Particles vibrate in place – they cannot move from one position to another.

Very strong forces of attraction – particles are held closely together.

Question 2

property of liquid

Answer 2

No fixed shape – takes the shape of its container.

Fixed volume – does not change size much.

Particles can move past each other – allows liquids to flow.

Medium forces of attraction – weaker than solids but stronger than gases.

Question 3

property of gas

Answer 3

No fixed shape – fills the container.

No fixed volume – expands to fill all available space.

Particles move freely and quickly – random motion in all directions.

Very weak forces of attraction – particles are far apart.

Question 4

as temperature increases?

Answer 4

particles gain kinetic energy and move faster

Question 5

as temperature decreases?

Answer 5

particles lose kinetic energy and so moves slowly

Question 6

as temp increases in a solid?

Answer 6

As temperature increases, particles gain kinetic energy and vibrate more rapidly about their fixed positions

Question 7

as temp increases in a liquid?

Answer 7

As temperature increases, particles gain kinetic energy and move faster, sliding past each other more quickly.

Question 8

as temp increases in a gas?

Answer 8

increases the average kinetic energy of gas particles, so they move faster and collide more strongly with the container’s walls.

Question 9

brownian motion

Answer 9

random movement of small particles suspended in a fluid, caused by collisions with fast-moving molecules of the fluid.

Question 10

solid

Answer 10

Fixed shape and fixed volume.

Cannot be compressed easily.

Strong structure.

Question 11

liquid

Answer 11

No fixed shape (takes shape of container).

Fixed volume.

Difficult to compress.

Question 12

gas

Answer 12

No fixed shape.

No fixed volume.

Easily compressed.

Low density.

Question 13

compress

Answer 13

To compress a substance means to reduce its volume by applying pressure.

Question 14

why are gases easy to compress?

Answer 14

easily compressed because there is a large distance between particles,

Question 15

why are solid and liquid not easy to compress?

Answer 15

solids and liquids are not compressible because their particles are closely packed.

Question 16

how does brownian motion occur?

Answer 16

It is caused by random and unequal collisions between the suspended particles and the much smaller, fast-moving molecules of the surrounding gas or liquid. These unequal collisions cause the particles to move in an irregular way.

Question 17

how is pressure caused in gas?

Answer 17

caused by gas particles moving randomly and colliding with the walls of the container. Each collision exerts a force on the surface. The combined effect of these collisions produces a force per unit area, which is the pressure of the gas.

Question 18

thermal expansion

Answer 18

the increase in size of a substance when it is heated because the particles gain kinetic energy and move further apart.

Question 19

temp and volum change in a gas

Answer 19

Temperature ↑ → particles move faster → pressure ↑

Volume ↓ → particles hit walls more often → pressure ↑

Question 20

what expands the least?

Answer 20

solid

Question 21

what expands the most?

Answer 21

gas

Question 22

melting point of water

Answer 22

0 degree

Question 23

boiling point of water

Answer 23

100 degree

Question 24

condensation

Answer 24

occurs when gas particles lose kinetic energy, move more slowly, and come closer together due to attractive forces, forming a liquid.

Question 25

solidification

Answer 25

occurs when liquid particles lose kinetic energy, move closer together, and are held in fixed positions by strong forces of attraction, forming a solid.

Question 26

evaporation

Answer 26

occurs when the more energetic particles at the surface of a liquid gain enough kinetic energy to overcome the forces of attraction and escape into the air as a gas.

Question 27

why does evaporation causes cooling?

Answer 27

causes cooling because the most energetic particles leave the surface of the liquid, reducing the average kinetic energy of the remaining particles, so the temperature decreases.

Question 28

easy evaporation remembering process

Answer 28

High-energy particles escape → average kinetic energy decreases → temperature decreases → cooling occurs.

Question 29

melting

Answer 29

the change of state from solid to liquid when heat is supplied.

Question 30

boiling

Answer 30

the change of state from liquid to gas throughout the liquid when heat is supplied.

Question 31

thermal expansion example

Answer 31

-gaps in railway track -expansion joint bridge

Question 32

difference between boiling and evaporation?

Answer 32

Boiling happens throughout the liquid at a fixed temperature (boiling point). Evaporation happens only at the surface and can occur at any temperature below the boiling point.

Question 33

increase in temp, surface area and wind movement regarding evaporation

Answer 33

Higher temperature → faster evaporation Larger surface area → faster evaporation More wind/air movement → faster evaporation

Question 34

thermal conductor

Answer 34

a material that allows heat energy to pass through it easily.

Question 35

examples of good and bad thermal conductor

Answer 35

-metals(good conductor) -non-metals(usually insulators)

Question 36

thermal conduction

Answer 36

the transfer of thermal energy from a region of higher temperature to a region of lower temperature without the movement of the material.

Question 37

Thermal conduction in a solid

Answer 37

occurs when particles vibrate more strongly after heating and transfer energy to neighbouring particles through collisions.

Question 38

thermal conduction in a metal

Answer 38

conduction is also due to delocalised electrons that move through the structure and transfer energy rapidly

Question 39

convection

Answer 39

The transfer of thermal energy in a fluid (liquid or gas) by the movement of the fluid particles.

Question 40

convection in liquid

Answer 40

The particles at the bottom are heated. They gain kinetic energy and move faster. The liquid expands and becomes less dense. Because it is less dense, it rises. The cooler, denser liquid sinks to take its place. This continuous movement forms a convection current.

Question 41

convection in gas

Answer 41

The gas is heated. The particles gain kinetic energy and move faster. The gas expands. It becomes less dense. The warm, less dense gas rises. The cooler, denser gas sinks. This creates convection currents.

Question 42

convection current

Answer 42

circular movement of a fluid caused by the rising of warmer, less dense fluid and the sinking of cooler, denser fluid.

Question 43

thermal radiation

Answer 43

transfer of thermal energy by infrared radiation. It does not require a medium and can travel through a vacuum.

Question 44

thermal energy

Answer 44

total internal energy of a substance due to the motion and arrangement of its particles.

Question 45

good absorbers and emitters of thermal radiation but poor reflectors.

Answer 45

black/dull surface

Question 46

poor absorbers and emitters but good reflectors of thermal radiation.

Answer 46

white/shiny surface

Question 47

Earth's temp dependance

Answer 47

If absorbed > emitted → Earth warms up. If emitted > absorbed → Earth cools down. If they are equal → temperature stays constant.

Question 48

what does convection,cnduction and radiation need for kt to happen?

Answer 48

Conduction → needs particles (solids mainly) Convection → needs a fluid (liquid or gas) Radiation → does NOT need anything