Energy

Conservation of Energy

• You cannot creat energy or destroy it. But you can transform it into another form.

• Eg energy from burning coal – ends up as kinetic energy or heat energy in a machine (steam train).

Conservation of Energy

• Energy can be converted/transformed from one form to another, but it cannot be created or destroyed.

Force Meters

• Newton Spring Balance• A spring stretches when a pulling force acts on

it• A spring gets squashed or compressed when a

forces pushes on it.• A spring can be used to measure the strength

of forces• What unit do we measure force in?

Measuring Force

• The unit used to measure force is the newton (N)• What is the force to lift an apple?– 1N

• Force to lift a 1kg bag of sugar– 10N

• Force you exert by sitting on someone– 400N

• Force needed to launch a rocket– 33000 000N

Comparing weight and mass

• Collect a series of objects that you can weigh with scales and then measure with the spring force.

• Write a data table showing the weight in g or kg and then N using the spring force. Remember the spring force measures the strength of force.

• Write a conclusion about what you notice.• When finished, use your spring force to measure

friction by pulling at item across the carpet, then the desk. Did you use more force on a different surface?

• Exercises page 236 and 237