# Thermal Physics J1 Hydra (Due : Friday 10/6) Abu Habib
Get Started. It's Free Thermal Physics J1 Hydra (Due : Friday 10/6) ## 1. Thermal Properties and Temperature (Charlotte, Jina, William, Ankit, Umar)

### 1.1. Thermal Expansion

1.1.1. When matter is heated it expands

1.1.1.1. Because molecules move faster when heated; therefore expanding the object

### 1.2. Thermal Contraction

1.2.1. When matter is cooled it contracts

1.2.1.1. Because molecules move slower and into a fixed pattern when cooled; therefore contracting the object

### 1.3. Measurement of Temperature

1.3.1. Units: Celsius (°C), Fahrenheit (ºF), Kelvin (K)

### 1.4. Thermal Capacity (Jina)

1.4.1. What is Heat Capacity?

1.4.1.1. The amount of heat required to increase the temperature of a substance by 1°C

1.4.1.2. Heat Capacity = Heat absorbed/ Change in temperature

1.4.1.2.1. C = 𝑸/ ∆𝑻

1.4.1.2.2. Heat absorbed ( or released)/ Energy is measured in joules (J)

1.4.1.2.3. Heat Capacity = Mass x Specific Heat Capacity

1.4.1.3. Units: J/°C or J/K

1.4.1.4. Heat capacity of an object depends on

1.4.1.4.1. Mass of an object

1.4.1.4.2. Type of material

1.4.2. Heat Capacity vs Mass

1.4.2.1. Heat capacity is directly proportional to mass

1.4.2.1.1. C = K m

1.4.3. Specific Heat Capacity

1.4.3.1. The amount of heat required to increase the temperature of 1kg of substance by 1°C

1.4.3.2. Specific Heat Capacity = Heat Capacity/ Mass

1.4.3.2.1. Cs = C / m

1.4.3.2.2. Cs = 𝑸 / m∆𝑻

1.4.3.3. Units: J/kg °C or J/kg

1.4.3.4. Specific Heat Capacity of an object only depends on Type of Material

1.4.3.5. Measuring Specific Heat Capacity

1.4.3.5.1. Energy and Power

1.4.3.5.2. Water

1.4.3.5.3. Aluminium

1.4.3.5.4. Other Metal

### 1.5. Melting and Boiling

1.5.1. Melting

1.5.1.1. Takes place at a definite temperature - 'melting point'

1.5.1.2. Thermal energy must be provided to break the bonds between molecules for them to leave well-ordered structure of solid

1.5.2. Boiling

1.5.2.1. Occurs at a definite temperature - 'boiling point

1.5.2.2. Bubbles of vapour form within the liquid and rise freely to the surface

1.5.2.3. Energy must be supplied continuously to maintain boiling

### 1.6. Heat Capacity [Ankit]

1.6.1. The amount of heat required to increase the temperature of a substance by 1 °C or by 1°K.

1.6.1.1. Formula; C= Q/ΔT

1.6.1.1.1. C = Heat Capacity

1.6.1.1.2. Q = Heat absorbed/released

1.6.1.1.3. ΔT = Change in temperature

1.6.1.2. Variables that affect heat capacity

1.6.1.2.1. Mass of the object

1.6.1.2.2. Type of material

1.6.2. Specific Heat Capacity

1.6.2.1. The amount of heat required to increase the temperature of 1 kg of substance by 1 °C or 1 °K.

1.6.2.1.1. Formula; C=Q/mΔT

1.6.2.1.2. Variables that affect heat capacity

## 2. Thermal Processes (fiza, harun, colin,ciara)

### 2.1. Convection (Colin)

2.1.1. Transfer of thermal energy (heat) from particles with more thermal energy to particles with less thermal energy in a gas or liquid.

2.1.1.1. Convection Current

2.1.1.1.1. Diagram

2.1.1.1.2. It is the process where a circulating stream is formed due to the difference in densities between particles with less thermal energy and particles with more thermal energy.

2.1.1.1.3. Daytime

2.1.1.1.4. Nighttime

### 2.2. Conduction (Colin)

2.2.1. Thermal energy (heat) is transferred from particles with more thermal energy to particles with less thermal energy through the direct contact between particles

2.2.1.1. Insulators (Poor conductors)

2.2.1.1.1. examples

2.2.1.2. Good conductors

2.2.1.2.1. examples

2.2.1.3. How do materials conduct?

2.2.1.3.1. When a material is heated, its particles move faster whilst pushing their neighbouring particles and speed them up too.

2.3.1. Thermal radiation is a mixture of different wavelengths. This occurs when infrared waves and lights travel through a vacuum (empty space) and heat up things that absorb them

2.3.1.1. Emitters and absorbers

2.3.1.1.1. good emitters and absorbers ( emits and absorbs at a fast rate)

2.3.1.1.3. comparing emitters and absorbers

2.3.1.2. Greenhouse effects

2.3.1.2.1. Thermal energy (from Sun) gets trapped by the atmosphere because some gasses absorb energy at different wavelengths. The heat-trapping action of the atmosphere

2.3.1.2.2. Greenhouses act as heat traps, as the thermal radiation passes through the glass/plastic, but gets trapped. The ground inside warms up and heats the air.

2.3.1.3. Solar panels

2.3.1.3.1. Solar panels on some roofs uses thermal radiation to heat up the water for the house. In the solar panel, a blackened layer absorbs the energy.

2.3.1.3.2. thermal energy ( from Sun ) → blackened layer ( insulated ) → water tank → pump

2.3.1.4.1. general function and idea

2.3.1.4.2. features

### 2.4. Consequences of energy transfer (Fiza)

2.4.1. conduction

2.4.1.1. using insulating materials

2.4.1.1.1. to reduce heat loss from a house

2.4.2. convection

2.4.2.1. what is caused by convection?

2.4.2.1.1. land breeze

2.4.2.1.2. sea breeze

2.4.2.2. uses of convection

2.4.2.2.1. car engines

2.4.2.2.2. glider pilots

2.4.2.2.3. air conditioning

2.4.3.1. greenhouse effects

2.4.3.1.1. without the heat trapping action of the greenhouse effects, the Earth's surface would be around 25ºC cooler

2.4.3.2. used a source of heat/thermal transfer

2.4.3.2.2. solar panel

## 3. Simple Kinetic Model of Matter

### 3.1. Kinetic Theory

3.1.1. Explains the behaviour of matter

3.1.2. Matter consists of large number of small particles

3.1.3. Separation between particles: caused by intermolecular forced

3.1.4. Particles are always in constant motion

3.1.5. Evidence: Brownian Motion (Solange)

3.1.5.1. The random motion of smoke particles seen by reflected light

3.1.5.2. Due to collisions with fast-moving air molecules in glass cell

3.1.5.3. Particles wobble in zig-zag paths

3.1.6. Energy of Particles (Solange)

3.1.6.1. Kinetic Energy: constantly moving

3.1.6.2. Potential Energy: motion keeps them separated & oppose the bonds trying to pull them together

3.1.6.3. Thermal Energy: total amount of internal energy possessed by the particles in an object

3.1.6.4. Internal Energy = Kinetic Energy + Potential Energy

3.1.6.4.1. The hotter a material is, the faster its particles move and the more internal energy it has.

3.1.6.5. Atom: smallest possible amount of an element. They have no colour or precise shape.

3.1.7. Solids, Liquid and Gases

3.1.7.1. Solids: Particles are held closely together by strong forces of attraction. They only vibrate by their own equilibrium position and can't change positions. Solids have fixed shape and volume

3.1.7.2. Liquids: Particles are close together and attract each other. Their attraction is not strong enough to hold them in fixed position and can move past each other.

3.1.7.3. Gas: The particles are well spread out and free to move randomly at high speeds and collide with one another.

3.1.8. Separation between particles: caused by intermolecular forced

3.1.9. Separation between particles: caused by intermolecular forced

3.1.10. Separation between particles: caused by intermolecular forced

### 3.2. Gas Laws (Solange)

3.2.1. Volume (V) : Meter³/m³ Temperature (T) : Kelvin/K Pressure (P) : Pascal/Pa

3.2.2. Boyle's Law P1V1=P2V2

3.2.2.1. For a fixed mass of gas at constant temperature, the pressure is inversely proportional to the volume

3.2.3. Charles' Law V1/T1=V2/T2

3.2.3.1. For a fixed mass of gas at constant pressure, the volume is directly proportional to the temperature

3.2.4. Gay-Lussac's Law P1/T1=P2/T2

3.2.4.1. For a fixed mass of gas at constant volume, the pressure is directly proportional to the temperature

### 3.3. Temperature ,Heat and Eqilibrium

3.3.1. temperature

3.3.1.1. the measure of average kinetic energy in a substance

3.3.2. heat

3.3.2.1. the amount of thermal energy transferred

### 3.4. Boyles Law

3.4.1. Boyles Law is a law about Ideal Gases . It states that For a fixed amount of an ideal gas kept at a fixed temperature, P (pressure) and V (volume) are inversely proportional.

3.4.2. PV=k

3.4.3. eg .In a gas, the molecules are constantly striking and bouncing of the walls of container. The force of these impacts causes pressure. If the volume of a fixed mass of gas is halved, by halving the volume of the container, the number of molecules per cm3 will be doubled. There will be twice as many collisions per second with the walls. Therefore, the pressure is doubled.

3.4.4. P1V1=P2V2

### 3.5. Charles Law

3.5.1. Charles Law is an experimental gas law that talks about how gases expand when heated

3.5.2. When the air inside the chamber is heated with a heating source via water, the temperature of the air increases and the kinetic energy associated with the molecules of the air increases. This momentary increases the pressure inside the chamber. Now, the molecules of the air exert more force in the outwards direction on the resting piston, and the air inside the chamber expands.

3.5.3. V1÷T1=V2÷T2

### 3.6. Gay-Lussac's Law

3.6.1. Gay-Lussac's law is a form of the ideal gas law in which gas volume is kept constant. When volume is held constant, pressure of a gas is directly proportional to its temperature

3.6.2. When a gas is heated and its temperature rises, the average speed of its molecules increases. If the volume of the gas stays constant, its pressure increases because there are more frequent and more violent collisions of the molecules with the walls.

3.6.3. P1÷T1=P2÷T2