While carrying loads up a flight of stairs, your students demonstrate the concepts of ‘work’, ‘energy’ and ‘power’. The "Work, energy, power" worksheet helps students to compare, connect and understand the terms, while the teaching notes below provide a deeper exploration of the terms to support learning.
Before you move into the hallway of your school, or wherever else you can find a flight of stairs, engage your students in a discussion of work. Ask students what requires more work: lifting a feather or pushing hard against a wall?
Ask students for definitions of the terms ‘work’, ‘power’, and ‘energy’. Do they have any ideas about how these three concepts are connected?
You’re introducing new terms with this activity, so focus your assessment on identifying what your students already know, and what they learn.
Discuss these two problems as a class:
The words work, energy and power will likely have different meanings for students than the scientific meanings we associate with electricity and other forms of energy.
In scientific terms, work is defined as the transformation or conversion of energy. Work is measured in joules (J).
Energy is the ability or capacity to do work and is also measured in joules (J). There are many different forms of energy (heat, light, electric, elastic, etc.) but all energy is either potential or kinetic.
Power is the rate at which energy is transformed or the rate at which work is done. Power (P) is measured in watts (W) or joules per second (J/s). Power can be calculated if you know the work (or energy) and time: Power = Energy / time (or P=E/t).
Electrical Power is the amount of electrical energy that is changed into other forms of energy each second. A good example of this is a 100-watt light bulb, which changes 100 joules of electrical energy into light and heat each second.
Electrical power can also be calculated if you know the voltage and the current in a circuit. Voltage is represented by ‘V’ and current is ‘I’.
Power = Current x Voltage (or P= I x V)