aqa physics - energy changes in systems

why do some materials need more energy to heat up than others?

because they require more energy to be transferred to their thermal energy stores

what happens when materials that need lots of energy to heat up cool down?

they transfer a lot of energy when they cool down

what is specific heat capacity?

the amount of energy needed to raise the temperature of 1kg of a substance by 1°c

what is the equation for change in thermal energy?

change in thermal energy (j) = mass (kg) × specific heat capacity (j/kg°c) × change in temperature (°c)

what equipment is needed to investigate specific heat capacity?

a solid block with two holes, an insulating layer, a thermometer, a heater, a power supply, and a stopwatch

why do you wrap the block in an insulating layer?

to reduce energy transferred to the surroundings

what happens when you turn on the power supply?

the current does work on the heater, transferring energy to the block’s thermal energy store by heating

how often should you record temperature and current?

every minute for 10 minutes

what should you notice about the current during the experiment?

it stays the same as the block heats up

how do you calculate power supplied to the heater?

p = v × i

how do you calculate energy transferred to the heater?

e = p × t

what graph should you plot to find specific heat capacity?

energy transferred to the block against temperature

how do you calculate specific heat capacity from the graph?

1 ÷ (gradient × mass of the block)