Topic 3 - Thermal Physics

Question 1

What type of motion is evidence for the kinetic model?

Answer 1

The brownian motion

Question 2

Describe Brownian motion with liquid

Answer 2

Microscopic solid particles move within a fluid even when it isn’t moving, they can be seen to move in random directions. Pollen grains can be suspended on water and viewed through a microscope.

Question 3

Describe brownian motion with air

Answer 3

Smoke particles can be suspended in air and seen to move moving in random zig-zag directions.

Question 4

What and how does Brownian motion show us?

Answer 4

That the kinetic theory is correct and larger microscopic particles will change direction when suspended in liquid or air due to a change in momentum. Smaller atoms or molecules will have the speed to change the momentum and direction of larger microscopic particles

Question 5

What are the three factors effecting pressure?

Answer 5

Volume, temperature and concentration

Question 6

What happened to pressure as temperature changes at a fixed volume?

Answer 6

An increase in temperature means the gas will have more energy and cause more collisions therefore increasing pressure

Question 7

What happens to pressure as volume changes at a fixed temperature?

Answer 7

As volume decrease there is less room for the particles and so there will be more collisions increasing pressure

Question 8

What equation states what happens to pressure when volume changes at a fixed temperature?

Answer 8

pV = constant
Or
p1V1=p2V2

Question 9

What is the combines gas equation

Answer 9

p1V1/T1 = p2V2/T2

Question 10

What happens to a object as its temperature increases?

Answer 10

The average kinetic energy of all the particles in the object increases

Question 11

What is specific heat capacity?

Answer 11

The energy required per unit mass per unit temperature increase. Or the energy required to heat 1kg of a material 1degree

Question 12

What is the equation for specific heat capacity?

Answer 12

c = change in energy / mass x change in temp
Or
Change in energy = c x m x change in t

Question 13

What is internal energy?

Answer 13

The total energy store by the particles making up as substance

Question 14

What is the specific heat capacity of water

Answer 14

4200J/Kg/Degree

Question 15

What are the three ways of heat transfer?

Answer 15

Convection
Conduction
Radiation

Question 16

What is conduction?

Answer 16

Conduction is the method of transferring heat down a solid object.
This is done by lattice vibrations giving energy to neighbouring particles and the movement of delocalised electrons in metallic conductors

Question 17

What is convection?

Answer 17

The transfer of heat through fluids.
As particles heat up they gain energy and move around
Particles that have energy will move from the hotter area to the cooler
So hot particles become less dense and rise
As they rise they loose energy and cool down
It creates a convection current

Question 18

What is a radiation?

Answer 18

A heat transfer method that uses infrared waves to travel through a vacuum

Question 19

What surfaces cause radiation to happen quickest and slowest?

Answer 19

Shiny white surfaces will absorb heat slowly whereas dull black surfaces will absorb heat faster
Shiny whiter surfaces will emit heat slowly whereas dull black surfaces will emit heat faster

Question 20

How can you investigate emission of radiation?

Answer 20

Using a Leslie cube - cube with different types of surfaces, you can detect the infrared emission on each side

Question 21

How can you investigate absorption of radiation?

Answer 21

With melting wax. Places four sheets of identical metal plates round a Bunsen burner but they all have a different surface facing the burner. On th outside a ball bearing is stuck on with wax. How quickly the wax melts will determine how well the surface absorbs radiation