Tpic 5 Thermal Phsyics (Year Ten)

Question 1

Wht ia Speicific heat capacity

Answer 1

The amount of energy required to raise the temperature of 1kg of rhe substance by degree

Question 2

Calculate the energy needed to increase the temperature of 2k of ater by 20degrees to 100 speicific heat capacity 4200 .

Answer 2

Change in thermal energy =mass (kg)speicifc heat capcicty J/kgChange in emperature.

Change in thermal neergy/
,assspecifccapcitytempchange .

Question 3

What is the RQP about ?

Answer 3

detemring the speicif cheat capacity of a subsatnce .

Question 4

first stage of the rqp

Answer 4

Beaker on abalance and press zero .
add oil and record mass of oil .

Question 5

second stage of the rqp

Answer 5

Place a thermometre and immerion heater into oil . Read starting tmp of oil .

Question 6

third stage of the rqp

Answer 6

Wrap bekaer in insualting material , reduces neergy thermal energy trandsfer to the surroudnings .

Question 7

fourth stage of the rqp

Answer 7

connect a joulemetre and power pack .
joeule metre tells us how many joules of energy is ging into the heater

Question 8

fifth stage of the rqp

Answer 8

Leave setup for 30 minutes - allows temperature to rise enough so we can accurately read on the thermimere .

Question 9

sixth stage of the rqp

Answer 9

Read total amount of joules of energy passed into immersion heater and the final temperature of the oil .

Question 10

seventh stage of the rqp

Answer 10

calculate specific heat capacity .

Question 11

What causes inaccuracy inthe RQP ?

Answer 11

Thermal neergy passing out of beaker into ait
SOLUTION
Using an insualtor with a lower themral conductivity .
Not all themra; eergy passiing into oil
SOLUTION
Ensure immersion heater is fully submerged .

Question 12

What cuases inaccuracy in the RQP ? (2)

Answer 12

Incorrect reading of thermoemeter
SOLUTION
use a electroinic tempeature probble
Thermal energy not spread evenly , stir the oil .

Question 13

What is latent heat

Answer 13

energy neeed for a substance o change state .

Question 14

What is specific latent heat

Answer 14

amount of energy required to change the state of one kg of a substance without changing its temperatrue .

Question 15

How much energy does it take to c=melt one kg of ice

Answer 15

334000J of neergy t o melt the kg o ice .
Scienits call this the speicif cltent heat of fusion .

Question 16

Specific altent heat of fusion ?

Answer 16

energyr equred to change ione kg o a substnnce from a solid to liquid withn o change in temprature .

Question 17

Chaning a liquid to gas
Specific latnet hea of vapourisaitn

Answer 17

Enegry needd to change one kg of a substance form a liquid ot a vapour with no change in tepmearture .

Question 18

Calculate energy change of a substance using what equaiton ?

Answer 18

E=ml
energychange u n (j)=mass(kg)the specific latnet heat in J/kg)
e/m*l trinagle

Question 19

What causes the pressure of gases ?

Answer 19

Due ot the particles colliding iwth the walls of the container tha gas is held in .
-By colldiign with walls o contianer , gas is exeritng a pressure .

Question 20

Lower temp …

Answer 20

lower kinetic energy , fewer collsions per second , and these are lower enegry collisons so low temp mean LOW PRESSURE.

Question 21

Higher temp …

Answer 21

hihger kinetic energy , more collisons per second , higher energy collisons , high temperture GAS PRESSURE HIGH

Question 22

What causes gas pressure

Answer 22

particle collsiosns cuases a force at eight angle to the wallas of th gas contianer , Forces acting oer the area of the ocntainer cases gas pressurre

Question 23

If we take the same gas , but increaseits voluem , while keeping the temperature constant…

Answer 23

we reduce the pressure . As we increases spacing ewen partciles , so particles travel much afsetr collding with the walls of contaienr .
Reducing number of particles collsiign per second with walls of container reducing temperature .

Question 24

The pressure of a gas …

Answer 24

is inversley porpotional to hte volume . If the volume increases , then pressure decresases .
SHOWN THORUGH EQUATION Pv=Constant - equation onlyture if temperature kept consant ,

double pressure half volueme
do qussitono n shee ,

Question 25

pressure increase
volume increase

Answer 25

volume increases
pressure decreases

Question 26

work don a bicyle pump

Answer 26

compressing gas , applying a force to postion , carried out work on gad .
-transgerred nergy to the gas particles and increased their internal neegry in the particles .
-increased neery of particles incfreased tmpe of gas .
[ump gets warm as we are doing work on gas increasign its internal energy .

Question 27

internal energy ?

Answer 27

KE and PE of particles.

Question 28

What is a leslies cube

Answer 28

-used to see how each surgave emiitts infrared iradiaition .Shiny black , Mattbalck , shiny silver ,white
matt not shiny
fill cube with hot wter
point infrared detector at each surae and record infrared emitted .

CONTROL SAME distancebetween leslies cubae and infrred detector so measurments are repeatbale .

Question 29

Alternative to using an infrared detector .

Answer 29

Use a thermoemter whth bulb pained balck .
PROBLEM - but resolution of thermoeter is less thn ifrared detecotr .
rESOLUTIO IS SMALLEST POSSIBEL CHNGE DTECTED , Slightest chnage dtecte dby infrared , but thermoeer may not see much difference betwee surfaces due to lower reoslution .

Question 30

Aborption of infrared

Answer 30

Infrared heater betweel two Metal paltes one shiny and one matt black .
vaseline on other sie with draing pins .
swith on ehater
and temperture of pates increase ,
time how long it takes to vseline to melt and draeing pin to fall of .

Question 31

Results

Answer 31

Mattacl absobrs the msot infrared and emmits most ,
Shiny material less as it tends to reflect hsiny mateiral .