Revision as of 13:34, 16 February 2010

Outcomes

• Pupils understand that work done is energy transferred.
• Pupils understand that power is the rate of doing work.
• Pupils can perform simple calculations of work done and power developed.

Specification References

• 4.9, 4.10, 4.13, 4.14

Main Body of Lesson

• Remind pupils of their previous work on energy transfers and the conservation of energy.
• Explain that transferring energy from one form to another is the process of doing work.
• State formula for calculating work done = force × distance.
• Pupils calculate the work done dragging a wooden block across their benchtop.
• Introduce equation for calculating (change in) gravitational potential energy as a form of the work done equation.
• Give pupils examples where the same amount of work is done in different amounts of time (e.g. riding a bike up the same hill quickly and slowly).
• Introduce the concept of power as the rate of doing work (i.e. power = work done / time taken). A more powerful device is able to convert energy from one form to another quicker than a less powerful device.
• Pupils calculate the power they developed in the previous running-up-and-down-the-stairs task.

Practicals/Demonstrations

• Pupils use newtonmeters to calculate work done (against friction) as they drag a wooden block across the benchtop.
• Pupils calculate the work done and the average power developed as they (repeatedly) climb a set of stairs.

Plenary

• Pupils sort a range of household devices (e.g. television, washing machine, power shower, oven, iPod, etc) into order of power consumption (slide available).

Homework

Additional Information

Resources Required

• Newtonmeters
• Wooden blocks with hooks

Safety/Hazards

• Overstretched newtonmeters can be hazardous.

Energy Outline

Energy