# Topic 1 - Thermal Energy Flashcards Preview

## Edexcel Physics IAL unit 5 > Topic 1 - Thermal Energy > Flashcards

Flashcards in Topic 1 - Thermal Energy Deck (23)
1
Q

The kinetic theory

A

The kinetic theory suggests that when energy is supplied to an object, it’s particles will take up the energy as KE and move faster

2
Q

TRUE OR FALSE:

Kinetic Energy determines temperatures.

A

TRUE

if the average KE of the molecules of a substance increases then it’s at a higher temperature

3
Q

Taking energy away from the molecules or a substance causes it’s temperature to become lower.

A

The kinetic theory suggests that if we remove all the kinetic energy from a substance then the molecules will no longer be moving. At this point the temperature is said to be Absolute Zero.

4
Q

What happens when you heat up one part of a metal rod?

A

The molecules on one end are moving more quickly (the hotter end) and there are more frequent collisions. While in the cooler parts the molecules are moving more slowly. When a molecule with high energy collides with one of low energy, they share the energy more evenly with the fast one slowing down and slow one speeding up

5
Q

The effect that transferred heat energy has on the temperature of an object depends on three things:

A
1. The amount of heat energy transferred
2. The mass of the object
3. The specific heat capacity of the material from which the object is made.
6
Q

What is specific heat capacity

A

It’s the amount of heat energy required to heat up 1 kg of a substance by 1 Kelvin (or 1 Celsius!)

7
Q

Specific heat capacity equation

A

E = mc /_\ T

8
Q

Internal energy

A

It’s the total sum of the Kinetic energy and the potential energy in a substance or object

9
Q

The kinetic energy will give the object it’s temperature

A

While the potential energy is due to the bonds between molecules

10
Q

Solids have equal amounts of KE and PE

While liquids have more KE but still have PE

A

Gases don’t have potential energy because there are no bonds between the molecules and so no attraction between them. They only have KE

11
Q

The Maxeell-Boltzmann distribution:

A

It’s important to note that:
• there are no molecules with zero energy
• only a few molecules have high energies
• there is no maximum value for the energy a molecule can have

12
Q

The graph is for specific temperatures

A

As the temp increases the peak moves towards higher energies (to the right) and therefore higher speeds

13
Q

The probable speed of the particles corresponds to the peak of the maxwell-Boltzmann distribution graph

A

The other speed is called the root-mean-square speed. This is the speed associated with the average KE
(1/2m = 3/2 kT) T must be in kelvin

14
Q

How is RMS found?

A
1. Square the individual speeds
2. Find the mean
3. Take square root
15
Q

Ideal gas properties:

A
1. The molecules have zero size
2. The molecules are identical
3. The molecules collide with each other and the walls of their containers elastically
4. The molecules exert no forces on each other except during collisions
5. There are enough molecules so that statistics can be applied
17
Q

Boyle’s law

A

For a constant mass of gas at a constant temperature, the pressure exerted by the gas is inversely proportional to the volume it occupies

18
Q

Charles’s law

A

For a constant mass of gas at a constant pressure, the volume occupied by the gas is proportional to its absolute temperature

19
Q

The pressure law:

A
• the average distance for each molecule between collisions is unchanged
• each molecule is traveling faster
• so there are more collisions per second
• each collision transfers momentum
• the force in the walls and hence the pressure increases
20
Q

Boyle’s law

A
• Each molecule has less distance to travel on average before collisions
• the number of collisions per second increases even though the speed is unchanged
• the momentum change per second increases
• pressure increases
21
Q

/_\ U = Q + W

A

Change in internal energy= heat energy supplied + work done on substance

22
Q

pV = nRT

OR

pV = nKT

A

The one with R is only used when (n) is the number of moles and R = 8.31

And K is Boltzmann constant when (n) is number of molecules

23
Q

A

It’s the number of molecules in one mole of gas = 6.022 x10^23

24
Q

The pressure law

A

For a constant mass at a constant volume, the pressure exerted by the gas is proportional to its absolute temperature