It is because it takes different amounts of energy (Joules) to heat 1 kg of different substances by 10C. 

So, when different substances are exposed to the same amount of Heat energy, they will change Temperature by different amounts.

When the sun shines, it gives the same amount of energy to both the sand and the water.

They will absorb the same amount of energy, but for this amount of energy, the sand will increase its Temperature more. 

This is because Sand has a lower "heat capacity" than water. 

This is referred to as the substance's Specific Heat Capacity.

For the same amount Heat Energy from the fire, the Iron Block will change its Temperature by the greatest amount because it has a lower heat capacity than water. 

So it will take less energy to change the temperature of 1kg of Iron.  

The Thermal Capacity is how much energy a substance is capable of absorbing before its temperature increases by 10C 

To put it another way:

It is the amount of energy (J) that 1Kg of a substance must absorb or release to change its temperature by 10C

To put it yet another way: 

The heat capacity is unique to a particular substance. Different substances have different heat capacities. To calculate the heat capacity of a substance, you measure how much energy you need to use to change 1kg of the mass by 10C in temperature:

Heat capacity (c) = Energy (J) / (1kg x 10C)

Heat capacity (c) = Energy [J] / (Mass [kg] x temperature change [0C])

E (thermal) = mcΔT 

E (thermal) = mcΔT 

But different metals have different Specific heat capacities. 

So when exposed to the same amount of heat energy, they will take different amounts of time to reach a specific temperature. 

If we take a kettle of boiling water and pour it into a cup. We then add a copper spoon and an aluminum spoon, which one will get hotter faster?

We can use the image to the side and see that the Specific Heat Capacities of the metals are as follows:

Copper: 390J per Kg per degree celcius

Aluminium: 910J per Kg per degree celsius

Energy: specific heat capacity x mass x change in temperature

Without doing the maths, we can see that it takes less energy for Copper to increase its temperature than it does Aluminium. So, it will be the Copper spoon that will get hot faster. 

Q and E(thermal) mean the same thing.  Q = E(Thermal) 

E = mL 

The formula to work out how much energy it takes to change the state of something: 

Heat Energy (Joules) = mass of substance (kg) x Latent Heat Energy (Joules per Kg)

The latent heat in Joules per kg is fixed for a substance. 

For example, water has a Latent Heat of Fusion of 334KJ per Kg. 

But water has a Latent Heat of Vaporisation of 2260KJ per Kg

This means you need less energy to melt snow than to evaporate water. 

This is good, because if it was the same amount of energy then the earth would be a dry desert and all of the water would be in clouds.

As it says in the document to the side "To change from a solid to a liquid, the bonds holdiong the particles together only need to 'loosen' a small amount. For a liquid to become a gas, the bonds holding the particles together need to be broken completly. The latent heat of vaporisation is always greater than the latent heat of fusion for any given substance"

Notice that the values for lead are lower than water. This might seem that lead should be a liquid. however, the Latent Heat of Fusion only applies once a substance is AT its MELTING Temperature. So, for Lead the block must be at 327 degrees celcius before you can apply the Latent Heat of Fusion to it.  

1. Heat Energy can move by Radiation 

• No atoms are needed

• It moves in electromagnetic waves

• Infra-red Radiation

• E.g from the Sun to the Earth, heat energy moves as waves of infrared radiation

• Black objects absorb radiant heat better, they also emit it better than white objects

  • This is why a chilly bin is white inside

Radiation is the transfer of heat through electromagnetic waves, primarily in the infrared part of the spectrum. Unlike conduction and convection, radiation does not require atoms to travel through. 

This is how the Sun’s heat travels through the vacuum of space to reach Earth. Any object with a temperature above absolute zero emits thermal radiation. 

Absorption and Emission: The color and texture of a surface influence how well it absorbs and emits radiant heat. 

Dark, matte surfaces (like black paint) are excellent absorbers and emitters of thermal radiation. 

Light, shiny surfaces (such as those found inside a chilly bin or an emergency blanket) are poor at absorbing and emitting heat, making them effective reflectors. This is why a chilly bin is often white or has a shiny interior—to reflect heat away and keep the contents cold.

What colour shirt is best to wear in the middle of summer, and which is the worst?

2. Heat Energy can move by Convection

• Convection currents: heat rises, cold sinks

• Liquids and gases: it involves flowing

• fluid movement

• How heat moves with an oil heater in your lounge, heat rises up to the ceiling, pushing down the cold air, which then gets hot. This takes time (so your heat pump is faster as it is pumping)

• Also, the reason your kettle has its heating element on the bottom of the bottle, not the top

When a fluid is heated, it expands and becomes less dense, causing it to rise rapidly. As this happens, cooler, denser fluid sinks to take its place, resulting in a continuous and efficient convection current.

Consider how a room heater operates: warm air rises and effectively pushes cooler air down to be heated. 

In a kettle, the heating element is strategically placed at the bottom, ensuring that the water heats efficiently as the warm water rises and the cooler water sinks. This process guarantees optimal heating throughout the entire kettle.

3. Heat Energy can move by Conduction.

• Solids: it involves touching

• Conduction = Direct Contact

• eg. wooden vs metal spoons in soup

  • The metal spoon will get hot, the wooden one will not

    • This is because the atoms in a metal are close together and can bump into each other, transferring the heat along the spoon. 

    • The wooden spoon has a more random arrangement of atoms, so they are less efficient bumpers

Conduction is how heat energy is transferred through direct contact in solids, where particles are closely packed. 

When one end of a solid is heated, its particles gain kinetic energy and vibrate more, passing these vibrations to neighboring particles, similar to a domino effect. This is why a metal spoon becomes hot when placed in hot soup.

Materials are classified as conductors or insulators based on heat transfer efficiency. Conductors, like metals, transfer heat well due to their mobile electrons. Insulators, such as wood or plastic, transfer heat poorly because their particles are less effective at passing vibrations.