Physics - Thermal Physics

Question 1

what is all matter made up of

Answer 1

microscopic particles which are constantly vibrating

Question 2

what does temperature determine

Answer 2

kinetic energy

Question 3

what is conduction

Answer 3

transfer of heat energy through transfer of kinetic energy between particles

Question 4

what do particles being heated do, and what does this cause

Answer 4

vibrate w greater amplitude
causes energy transfer throughout the system
mainly happens when particles are closely bound

Question 5

rank states of matter in order of best to work conductor

Answer 5

SOLID - particles bound closely

LIQUID - particles are further apart so takes longer for kinetic energy to be transferred

GASES - poorer conductors as particles diffuse and kinetic energy transfer is less efficient

Question 6

how is rate of conduction increased

Answer 6

• increasing temperature gradient
• decreasing distance between particles
• increasing surface area of particles surrounding matter

Question 7

what is a convection current

Answer 7

• when a fluid is heated, average speed of particles increases
• separation between these particles increases and the fluid expands
• as fluid expands, density decreases
• therefore, hotter, less dense fluids will rise and be replaced by less dense, colder fluid

Question 8

nature of convection

Answer 8

• much faster than conduction
• convection cannot occur in solids due to fixed nature of particles in relation to neighbouring particles

Question 9

what is a common example of convection

Answer 9

room heaters
heat air surrounding it, causing it to rise and circulate the room

Question 10

what is cavity wall insulation

Answer 10

inserted between two brick layers of buildings to prevent convection currents establishing which in turn reduces heat loss from buildings by convection

Question 11

thermal radiation speed

Answer 11

light

Question 12

thermal radiation energy transfer

Answer 12

doesnt require particles like conduction and convection do
can transfer energy in a vacuum
can be used to transfer energy to a far away object without heating space in between e.g. space heaters

Question 13

what does every object with a temperature above absolute zero emit

Answer 13

thermal radiation

Question 14

what happens when an object emits thermal radiation

Answer 14

thermal energy of object decreases

Question 15

what happens when thermal radiation hits an object

Answer 15

it is either absorbed, transmitted, reflected

absorption of radiation causes the temperature of the object to increase

if absorption is greater than emission, object’s temperature increases and vice versa

Question 16

is air a good absorber of thermal radiation

Answer 16

no

Question 17

why can thermal radiation from the sun pass through the atmosphere to the earth’s surface

Answer 17

because air is a poor absorber of thermal radiation

Question 18

are shiny objects good absorbers and emitters ?

Answer 18

they are poor absorbers and emitters of thermal energy

Question 19

are matte objects good absorbers and emitters ?

Answer 19

they are good absorbers and emitters of thermal energy

Question 20

specific heat capacity equation

Answer 20

thermal energy / (mass x temperature change)

Question 21

what is energy measured in

Answer 21

joules

Question 22

what is temperature measured in

Answer 22

celsius

Question 23

what is specific heat capacity measured in

Answer 23

J/Kg/C

Question 24

define specific heat capacity

Answer 24

energy transfer per unit mass per unit temperature change