Different materials have different specific heat capacities
More energy needs to be transferred to the thermal energy store of some materials to increase their temperature than others
Materials that need to gain lots of energy in their thermal energy stored to warm up also transfer lots of energy when they cool down again. They can 'store' a lot of energy
Specific heat capacity is the amout of energy needed to raise the temperature of 1kg of a substance by 1°C
∆E(J) = m(kg)c(J/kg°C)∆θ(°C)
Change in energy(J) = mass(kg) x specific heat capacity(J/kg°C) x temperature change(°C)