2.1 What is energy?

Energy is the ability to do work or cause

• events

• change

• friction

• explosions

Energy and work are measured in

• newtons

• joules

• hertz

• kilograms

How many joules are in 23 kJ

• 23000 J

• 0.023 J

• 230 J

How many kilojoules are in 2000 J?

• 20 kJ

• 0.02 kJ

• 2 kJ

How many kilojoules can we find in 10 kcal?

• 4.2 kJ

• 24 kJ

• 42 kJ

How many kcal can we find in 8.4 kJ?

• 0.5 kcal

• 5 kcal

• 2 kcal

Why is it important for young children to take in more energy than they use for their activities each day?

• Growth

• Talking

• Drinking

For how many minutes would you need to cycle to use up the energy in 100 g of rice?

(rice 500kJ)

(cycling consumes 25kJ/min)

• 15 min

• 2500 min

• 20 min

All activities have an energy cost.

• True.

• False.

One gram of wood stores a similar amount of energy to 1 g of chocolate.

• True.

• False.