Changes in energy

Key points:

• Energy can’t be created or destroyed. If one object loses energy, another object has to gain that energy.
• Energy can be converted into different forms. For instance, a hairdryer takes electrical energy and converts it into thermal energy.
• When an object’s motion changes, so does its energy. If a bicycle slows down, it loses kinetic energy. That kinetic energy will be converted into another form, such as thermal energy, or transferred to another object.
• When a force acts on an object the energy of that object changes. For instance, when you hit the brakes on a bike, you’re applying a force to the wheels. That force converts some of the kinetic energy into heat.