Topic 3 Thermal Physics

Question 0

Temperature in kelvin =

Answer 0

Temperature in Celsius +273

Question 1

Temperature

Answer 1

Is a property that determines the direction of heat flow between two bodies in thermal contact. It is also a measure of the average random kinetic energy of the molecules of an ideal gas.

Question 2

Kelvin temperature

Answer 2

Is proportional to the average kinetic energy if the particles

Question 3

Internal energy

Answer 3

Is the total potential energy and random kinetic energy of the particles in a substance

Question 4

Thermal capacity

Answer 4

Of an object is the amount if energy needed to raise the temperature of the object by 1k

Question 5

Specific heat capacity

Answer 5

Is the amount if energy needed to raise the temperature if unit lads of a substance by 1K

Question 6

Specific latent heat

Answer 6

Is the amount of thermal energy needed to change the state of a unit made of a substance at a Constance temperature

Question 7

A mole

Answer 7

I the amount of a substance that contains the same number of atoms as 0.012 kg if carbon-12

Question 8

Molar mass

Answer 8

Is the mass of one mole of a substance

Question 9

The Avogadro Constant

Answer 9

Is the number of atoms in 0.012kg of carbon-12 (approx 6 x 10^23)

Question 10

Pressure

Answer 10

Is defined as the normal force to an area per unit area

Question 11

Ideal gas assumptions:

Six points

Answer 11

1. A gas consists of a large number of molecules
2. Molecules move with a range of speeds
3. The volume of the molecules is negligible compares with the volume of the gas itself
4. The collisions of the molecules with each other and the container walls are elastic
5. Molecules exert no forces on each other or the container except when in contact
6. The duration of collisions is very small compared with the time between collisions
7. The molecules obey Newton’s laws of mechanics

Question 12

Isobaric process

Answer 12

Pressure stays constant

Question 13

Isochoric process

Answer 13

Volume stays constant

Question 14

Isothermal process

Answer 14

Temperature and internal energy stay constant. The change is usually slow so that the temperature always equalises.

Question 15

Adiabatic process

Answer 15

No thermal energy enters or leaves the system in an adiabatic change. It is usually fast so there is no time for thermal energy to be exchanged.

Question 16

Isothermal and adiabatic expansion

Answer 16

Goes down

Question 17

Isothermal and adiabatic compression

Answer 17

Goes up

Question 18

Expansion

Answer 18

Adiabatic is steeper downwards

Question 19

Compression

Answer 19

Adiabatic is steeper than isothermal