thermal

Question 1

define internal energy

Answer 1

the sum of randomly distributed potential and kinetic energies of the particles in a body

Question 2

how does the internal energy of the system increase

Answer 2

-heat energy is transferred
-work is done on the system

Question 3

equation of first law of thermodynamics

Answer 3

Q=change in U+W
U=internal energy
W=work done by the system
Q=heat added

Question 4

define specific heat capacity

Answer 4

the amount of energy required to increase the temperature of 1 kg of the substance by 1C without changing its state

Question 5

define specific latent heat of fusion/vaporisation

Answer 5

energy required to change the state of 1 kg of the substance from _ to _ without changing its temperature

Question 6

how to calculate delta theta

Answer 6

final temperature - initial temperature

Question 7

what cancels out in the continuous flow calorimeter calculation

Answer 7

heat loss, as in this experiment delta theta is set to be constant so heat loss is also constant

Question 8

explain why an electric motor become warm when it is used

Answer 8

-work is done by the magnetic field
-electrons collides and gives up some of their energy in the wire

Question 9

describe the energy transfer in the electric motor

Answer 9

-electrical energy converted to kinetic energy and heat energy in the motor,
-heat energy transferred to the surrounding from the motor

Question 10

what is absolute zero temperature

Answer 10

0K,=-273C

Question 11

what is Boyle’s law

Answer 11

p1V1=p2V2, constant temperature

Question 12

what is Pressure’s law

Answer 12

p1/T1=p2/T2

Question 13

what is Charles’s law

Answer 13

V1/T1=V2/T2

Question 14

the steeper the gradient in volume against temperature graph means that

Answer 14

the lower the pressure

Question 15

the further the curve away from the origin in pressure against volume graph

Answer 15

the higher the temperature

Question 16

difference between n and N

Answer 16

n=moles , N=number of molecules, N=Avogadro*n

Question 17

equation for work done

Answer 17

W=p*change in V

Question 18

define Avogadro’s constant

Answer 18

the number of molecules in one mole of a substance/ the number of atoms in 12g of carbon-12

Question 19

For ideal gas, all molecules of a gas are identical so they have the same

Answer 19

mass and change in momentum on average

Question 20

describe the motion of ideal gas

Answer 20

molecules move in random motion

Question 21

How do ideal gas collide

Answer 21

elastic collision, KE is conserved

Question 22

How does it mean when ideal gas said to be following the newton’s 1st law

Answer 22

the molecules move in straight

Question 23

assumption on the volume for ideal gas

Answer 23

the volume of molecules is negligible compared to the volume of the gas

Question 24

large amount of molecules for ideal gas so

Answer 24

constant force on the wall

Question 25

what can we say about the attraction between molecules in ideal gas

Answer 25

no attraction so potential energy is zero

Question 26

assumption on time for ideal gas

Answer 26

the duration of collisions is negligible compared to the time between each collisions

Question 27

how to derive pV=1/3Nm(c rms)^2

Answer 27

-change in momentum for each molecules -one round trip in t time -times them to get the total change in momentum of one molecule -divide the total N by 3 as molecules move in random motion -time it by the total change in momentum -find F , F=mv/t -find p, substitute in V

Question 28

equation for total kinetic energy of molecule in ideal gas

Answer 28

KE=3/2nRT

Question 29

methodology for answering KE model explanation

Answer 29

-effects on collisions per second/mean KE due to___ - effects on change in momentum and rate of change in momentum -force is proportional to pressure