Thermal Physics

Question 1

what are the 3 states of matter

Answer 1

solid, liquid, gas

Question 2

properties of solids

Answer 2

• fixed shape
• high density
• cant be compressed
• low energy
• vibrate around fixed position

Question 3

properties of liquids

Answer 3

• can flow or be poured
• fill the container
• cant be compressed
• medium density
• randomly arranged

Question 4

properties of gases

Answer 4

• can flow to take shape of container
• can be compressed
• low density
• move quickly in all directions
• randomly arranged
• highest energy

Question 5

process from solid to liquid

Answer 5

melting

Question 6

process from liquid to gas

Answer 6

evaporation/boiling

Question 7

process from gas to liquid

Answer 7

condensation

Question 8

process from liquid to solid

Answer 8

freezing

Question 9

process from solid to gas

Answer 9

sublimation

Question 10

process from gas to solid

Answer 10

deposition

Question 11

what is temperature

Answer 11

average kinetic energy

Question 12

amount of pressure that a gas exerts on its container it dependent on the…..

Answer 12

….temperature of the gas

Question 13

what is absolute zero

Answer 13

temperature at which particles in a gas exert no pressure and are no longer moving, hence not colliding with their container

Question 14

what is the value of absolute zero

Answer 14

-273ºC

Question 15

what causes pressure in a gas

Answer 15

collisions with the surface of its container

Question 16

what is brownian motion

Answer 16

random motion of microscopic particles in a suspended by a liquid or gas, caused by collisions between these particles and the liquid or gas

Question 17

what is brownian motion an evidence of

Answer 17

kinetic particle model of matter

Question 18

what is pressure

Answer 18

force per unit area

Question 19

why do gases at high pressure have a greater force

Answer 19

• as particles move around randomly, they collide with the walls of their container
• these collisions produce a net force at right angles to the wall of the gas

Question 20

what happens to the pressure if the temperature of a gas increases at constant volume

Answer 20

increases

Question 21

what happens to the pressure if you decrease the volume of the container at constant temperature

Answer 21

increases

Question 22

why do material expand when heated

Answer 22

molecules start to move around faster, which causes them to knock into each other and push each other apart

Question 23

applications/consequences of thermal expansion

Answer 23

• metal railway track expand and start to curve (buckling)
• buckling of road surfaces
• buckling of bridges

Question 24

expansion of solids

Answer 24

• expand slightly
• low energy molecules overcome th strong intermolecular force

Question 25

expansion in liquids

Answer 25

• expand more than solids
• molecules have enough energy to partially overcome the intermolecular force

Question 26

expansion in gases

Answer 26

• expand the most
• molecules have high energy to overcome the intermolecular force

Question 27

what does a rise in temperature cause

Answer 27

rise in internal energy (by increasing the kinetic enrgy)

Question 28

what is internal energy

Answer 28

total energy stored in a system by the particles that make up the system due to their motion and positions

Question 29

what is specific heat capacity

Answer 29

Energy required to change the temperature of 1 kg of the substance by 1 °C.

Question 30

evaporation

Answer 30

• occurs to any liquid at any temp and results in the cooling of the liquid
• molecules that hit the surface provide energy

Question 31

melting and boiling point of water

Answer 31

0 and 100

Question 32

boiling

Answer 32

• occurs to a liquid at certain temp and involves temperature input
• does not result in cooling of the liquid

Question 33

what is conduction

Answer 33

transfer of thermal energy from one object to another

Question 34

where does conduction occur

Answer 34

in solids

Question 35

how does conduction occur

Answer 35

• object is heated to atoms vibrate more rapidly
• increases vibrations and affects nearby atoms (lattice vibration)

Question 36

are non metals good conductors, why?

Answer 36

no due to slow lattice vibration and no delocalised electrons

Question 37

why are liquids and gases poor conductors

Answer 37

particles are too far from each other and rarely make contact to transfer energy

Question 38

experiment to test for conduction

Answer 38

• place rods of different materials into holes within a water tank
• place drawing pins at the end of each rod
• pour very hot water into the tank
• time how long it takes for each pin to fall of

Question 39

where does convection occur

Answer 39

liquids and gases

Question 40

how does convection occur

Answer 40

• when as gas or liquid is heated, its volume will increase
• so the density decreases and the gas will rise

Question 41

radiaton

Answer 41

• infrared radiation that all objects emit - Way of transferring heat from one place to another

Question 42

does radiation require a medium

Answer 42

nope nope nope

Question 43

which colours absorb and reflect heat

Answer 43

absorb = black
reflect = shiny (white)

Question 44

how can an object be at constant temperature

Answer 44

transfer energy away at same rate it receives

Question 45

experiment for radiation

Answer 45

• Place the Leslie’s cube on a heat-resistant surface and fill the cube with freshly boiled water.
• Place the back of your hand near each of the coloured surfaces in turn and compare how hot they feel.
• Point the infrared thermometer at each surface in turn to attempt to measure their temperature.