Heat and Temperature - SCI STAGE 9 S2A

Entire Unit 3: 3.1-3.6

Heat is the energy that flows from hotter regions to colder regions, it is the flow of energy from warmer to cooler places. It is a flow of energy due to temperature differences. It is the energy that moves.

What is heat?

It is the average energy (or speed) of particles in a substance.

What is temperature?

Thermal energy is the total energy of particles in a substance. Thermal energy refers to the energy contained within a system that is responsible for its temperature (so energy of particles, or total energy). It is the random kinetic energy of particles in an object.

What is thermal energy?

• Heat is the FLOW OF ENERGY from hotter to colder places.

• Temperature is the AVERAGE ENERGY OF PARTICLES in a substance.

• Thermal energy is the TOTAL HEAT ENERGY inside an object.

• Heat is the energy moving from hot to cold, temperature shows how hot something is, thermal energy is the total heat energy.

What is the difference between heat, temperature and thermal energy?

The main factors affecting heat transfer are the temperature difference between objects, the surface area involved, and the material's properties like its thermal conductivity. Other factors include the distance between objects, the type of heat transfer (conduction, convection, radiation), and the geometry or thickness of the material. 

What are the factors affecting heat transfer?

1. Potential energy - energy at rest

2. Kinetic energy - energy in motion

3. Gravitational energy - energy in gravity/falling

4. Thermal energy - energy of heated particles

5. Sound energy

6. Light energy

7. Elastic energy

8. Heat energy - when the digestive system is turning the food into enzymes already, it can release heat energy

List the types of energy.

1. The mass of the atoms in the substance.

2. The speed/vibrations of the atoms in the substance.

What factors affect temperature?

It is the amount of heat needed to raise the temperature of a substance by one degrees celsius.

What is specific heat capacity?

1. If a material has a high specific heat capacity, it means it takes a lot of heat to raise its temperature (eg. water).

2. If it has a low specific heat capacity, it heats up quickly, like metals.

What does it mean if a substance has a high/low specific heat capacity?

J/kg x degrees celsius

eg. water has a specific heat capacity of 4200 J/kg*C (replace the asterisk as a degree symbol), which means it needs 4200 joules of heat to warm it up by 1 degree celsius.

What is the unit of specific heat capacity?

Energy is never created nor destroyed, it can only be changed or transferred from one form to another. You cannot make energy from nothing. Energy always comes from something that already exists.

State the law of conservation.

A Sankey diagram is a visual tool used to show how energy is transferred in a system (or transported). A bigger arrow in the diagram represents more energy. A downward pointing arrow represents wasted energy, while forward pointing arrows to the right represent useful energy.

Whereas: Conservation of energy is observed → Input energy = useful energy + wasteful energy (output energy).

What is a Sankey diagram?

Dissipation is the spreading out of thermal energy. Dissipated energy is energy that spreads out into the surroundings and usually cannot be used to do useful work.

What is dissipation?

All of the particles that make up matter are constantly in motion. Particles of a solid will vibrate in fixed positions, particles of a liquid flow in motion, particles of a gas move freely, and particles of plasma move incredibly fast and freely.

What is the kinetic theory of matter?

Yes, they do. All liquids, gases and most solids expand when their temperature increases. This is called thermal expansion. This is why some bridges have short segments so that it allows for expansion when heated.

Do liquids, gases and solids expand when their temperature increases?

All matter is made up of atoms that are moving, even solids have particles that are vibrating. The motion from the atoms gives the object energy, which is the thermal energy needed for heat transfer, creating temperature.

Explain why temperature depends on particle movement.

Celsius: -273.15

Fahrenheit: -459.67

Kelvin: 0K

What is the temperature of absolute zero/absolute cold in celsius, fahrenheit, and kelvin?

Celsius to F: 9/5 x C +32

F to C: 5/9 x (F - 32)

K to C: K - 273

C to K: C + 273

How do you do the conversion of temperature units?