Quick questions on Energy, power and nutrition for HSC Maths Standard 2

A kilowatt-hour ($\text{kWh}$) is the energy a $1$ kW appliance uses in $1$ hour. It is the "unit" of electricity on a bill. To find the energy an appliance uses, multiply its power in kilowatts by the time it runs in hours:

The energy in food is measured in kilojoules ($\text{kJ}$); it is the chemical energy your body can release from the food. (You may see the old unit, the Calorie, where $1$ Cal $\approx 4.2$ kJ, but Australian labels and NESA use kilojoules.) Food energy is additive: the energy of a meal is the sum of the energy of its parts. Labels often quote energy "per $100$ g", so for a different amount you scale:

Your body uses energy even at complete rest - to breathe, pump blood and stay warm. That baseline rate is the basal metabolic rate (BMR), in kilojoules per day. Being active uses more, so your total daily need is the BMR scaled up by a physical activity level (PAL), also called an activity factor: