P2 (Thermal physics)

Question 1

Properties of a solid

Answer 1

-High density

-Fixed volume, cannot be compressed

-Fixed shape

-Cannot flow

Question 2

Properties of liquids

Answer 2

-High density

-Can flow

-Fixed volume, cannot be compressed

-Takes the shape of the container

Question 3

Properties of gases

Answer 3

high density

Flows very quickly

Can be compressed

Fills up the volume of the whole container

Question 4

Molecular structure of solids

Answer 4

arrangement:

-regularly arranged
-closely packed together
-Held in place by strong attractive forces

movement:
-Vibrate in place

Question 5

Molecular structure of liquids

Answer 5

arrangement:

-closely packed as in solids (thus not compressible)
- irregular, random pattern

movement:

slide past each other due to weaker imf than solid (thus liquids can flow and fill a container)

Question 6

Molecular structure of gases

Answer 6

arrangement:

far apart- more kinetic energy

randomly arranged

movement:

-flow quickly from place to place

-unlike liquids they fill the container

-move in straight line until collisions

Question 7

What happens to its particles as a gas cools?

Answer 7

slow down- eventually they will become closer and move slower so that forces can form between them

It becomes a liquid

Question 8

What happens to its particles as a liquid cools?

Answer 8

slow down- the particles lose enough energy to form a fixed structure- its become a solid

Question 9

What happens to its particles as a solid cools?

Answer 9

vibrations become smaller and smaller

Question 10

What is the pressure of a gas caused by?

Answer 10

The huge number of tiny collisions happening between the gas particles and the walls of the container

Question 11

What relationship does temperature and pressure have?

Answer 11

directly proportional

Temp ⬆️ pressure ⬆️
Temp ⬇️ pressure ⬇️

Question 12

What relationship does volume and pressure have?

Answer 12

inversely proportional

Volume ⬆️ pressure ⬇️
Volume ⬇️ pressure ⬆️

Question 13

What is brownian motion

Answer 13

The random, continuous movement of microscopic particles in a fluid (liquid or gas), caused by collisions with smaller, fast-moving molecules.

Question 14

explain the suspension in water method & smoke cell

Answer 14

suspension in water:
Tiny visible particles are suspended in a fluid (water or air)

Observed using a microscope (smoke cell also uses a light source)

smoke cell:
Smoke particles trapped in a sealed glass cell

Viewed using a microscope and light source

Question 15

What are the results of the smoke cell and water suspension method

Answer 15

Carbon particles move around inside the liquid water in a random pattern due to impacts with water molecules which are moving rapidly.

Smoke particles show similar behaviour when they are suspended in the air due to fast air molecules colliding with them.

Question 16

What states of matter can brownian motion be observed in

Answer 16

liquids and gases - as the particles are free to move and collide with smaller, visible particles

Question 17

As the temperature of a gas increases, the particles move ________. there fore they collide with walls of the container with more __________ and more ________

Answer 17

faster
force
frequently

Question 18

What does the increase in movement of particles cause

Answer 18

objects or materials to become slightly larger as they are warmed up

Question 19

What is thermal expansion?

Answer 19

the increase in the size of a solid, liquid, or gas when its temperature rises due to particle movement increasing and spreading further apart.

Question 20

How big is the force produced by a solid material?

Answer 20

very large

Question 21

Whats an example of thermal expansion in solids in real life

Answer 21

A long piece of metal, such as a railway line, can bend because of the large forces produced when it heats up on a sunny day.

Question 22

What are some methods of investigating thermal expansion?

Answer 22

Bimetallic strip

Flask of liquid

Question 23

what is a real life application of the liquid in flask method?

Answer 23

Thermometers: rely on the expansion of liquids to measure temperature

It consists of a thin glass capillary tube containing a liquids that expands with temperature

Question 24

Whats a real life application of the bimetallic strip method?

Answer 24

Temperature activated switches- consists of two metals that expand at different rates and bends by a predictable amount at a given temp.

Question 25

Whats a real life example of thermal expansion in gases?

Answer 25

hot air balloon: When the air inside the balloon is heated, the gas particles move faster and spread out, causing the air to expand. This makes the air less dense than the cooler air outside, causing the balloon to rise.

Question 26

What happens when water boils?

Answer 26

The liquid starts to change into a gas throughout, which results in bubbles of gas forming inside the liquid. When boiling, the liquid does not get any hotter. Water stays at 100 °C until it has all boiled away.

Question 27

What increases when a material heated?

Answer 27

its internal energy - we normally see a temp rise or a change of state

Question 28

What is the melting point, freezing point and boiling point of water?

Answer 28

0,0, 100 C

Question 29

What happens as a gas cools and reaches boiling point?

Answer 29

temp decrease stops. The arrangement of molecules changes and condensation occurs

Question 30

What is condensation?

Answer 30

When the molecules in a gas form stronger forces between themselves and end up much closer together,forming a liquid

Question 31

What happens as liquid cools to its melting point

Answer 31

the forces between the molecules become much stronger and they can no longer move about. Instead, they end up in fixed positions. Freezing happens

Question 32

What is evaporation?

Answer 32

the process by which a liquid turns into a gas at the surface, below its boiling point

Question 33

What happens when liquid evaporates?

Answer 33

faster-moving particles near the liquid's surface escape into the air, reducing the liquid's volume over time. Slower particles remain, as only the fastest can escape.

Question 34

What happens to the mean speed of the remaining particles in a liquid after evaporation?

Answer 34

decreases- the fastest particles escape first. This means that the speed thus temperature of the remaining liquid decreases

Question 35

What factors affect the rate of evaporation?

Answer 35

Temperature : Increases kinetic energy, speeding up evaporation or reactions. Surface Area: Larger surface area exposes more particles, increasing the rate of evaporation or reaction. Air Movement/Wind: Removes particles from the surface, speeding up evaporation by maintaining a concentration gradient

Question 36

when a material is heated, it will expand as particles move further apart, when it it is cooled it will ______

Answer 36

contract

Question 37

solids typically expand ______ than liquids because their particles are held in fixed positions

Answer 37

less

Question 38

What happens at points of change in state? (like melting points and boiling point)

Answer 38

temperature doesn't increase- het energy being provided doesn't increase the internal energy instead it is used to overcome the intermolecular forces between molecules

Question 39

What are good thermal conductors?

Answer 39

materials that allow heat to pass through them easily. These include metals such as: Copper Aluminum Silver Iron

Question 40

How does thermal conduction in solids work?

Answer 40

Molecules vibrate more when they have more energy​ The vibrations get passed from molecule to molecule​ ​In a metal, the free electrons also gain more kinetic energy and they move throughout the metal, colliding with other molecules.​

Question 41

Why are metals the best thermal conductors?

Answer 41

Free electrons

Question 42

What two mechanisms can conduction occur through?

Answer 42

Atomic vibration Free electron collisons

Question 43

explain convection on a molecular level.

Answer 43

When a liquid or gas is heated (e.g., by a radiator), its particles gain energy, move faster, and spread apart, causing expansion. This makes the fluid less dense than its surroundings, so it rises. Cooler, denser fluid moves in to replace it. As the rising fluid cools, it contracts, becomes denser, and sinks. This continuous cycle creates a convection current.

Question 44

What is thermal radiation?

Answer 44

The only way in which heat can travel through a vacuum. Heat energy transferred by electromagnetic waves- mainly infrared and visible light

Question 45

Thermal radiations does not need a ________ unlike _______ and ________

Answer 45

medium conduction convection

Question 46

The __________ an object is the more ___________ it emits

Answer 46

hotter thermal radiation

Question 47

How does heat from the sun reach us?

Answer 47

Thermal radiation- the only way in which heat can travel through a vacuum.

Question 48

Design an experiment investigating the relationship between colour and radiation.

Answer 48

equipment: 1 white can 1 black can 2 thermometers styrofoam lids method: Pour hot water into each can Measure the temperature of each can every 10 seconds possible sources of error: heat lost through conduction/convection which the lid will prevent (you may choose to add shiny and matte can to test it on texture)

Question 49

black dull surfaces __________ and ___________ more thermal radiation than _______, ________ surfaces

Answer 49

absorb emit white shiny

Question 50

Black objects are __________ absorbers and good _________

Answer 50

good emitters

Question 51

Dull/dark objects are ___________ absorbers and reasonable _________

Answer 51

reasonable emitters

Question 52

white objects are ___________ absorbers and ________ _________

Answer 52

poor poor emitters

Question 53

shiny objects are _______ _____ absorbers as it reflects and very ________ emitters

Answer 53

very poor poor

Question 54

explain the greenhouse effect

Answer 54

Greenhouse gases (e.g., CO₂ and water vapor) absorb and re-emit heat radiation from Earth's surface, trapping heat in the atmosphere and increasing global temperatures.

Question 55

What does the temperature of earth depend on

Answer 55

Energy received from the Sun (mainly as shortwave radiation). Energy radiated back into space (mainly as infrared radiation). The greenhouse effect, which traps heat in the atmosphere

Question 56

When you draw a thermometer in a test, what do you need to remember

Answer 56

draw the thermometer in the water

Question 57

what enables efficient convection

Answer 57

larger surface areaa

Question 58

why do solids have a fixed shape

Answer 58

strong forces of attraction between atoms hold atoms together in a fixed position