# 4.1.1.4 Power

## Content

Power is defined as the rate at which energy is transferred or the rate at which work is done.

power = energy transferred time

P = Et

power = work done

time

P = Wt

power, P, in watts, W

energy transferred, E, in joules, J

time, t, in seconds, s

work done, W, in joules, J

An energy transfer of 1 joule per second is equal to a power of 1 watt.

Students should be able to give examples that illustrate the definition of power eg comparing two electric motors that both lift the same weight through the same height but one does it faster than the other.

MS 3b Change the subject of an equation

MS 3c Substitute numerical values into algebraic equations using appropriate units for physical quantities

Lessons

P1.9 - Lesson for calcualting power.

Resources

Video iPhones Are Now Exploding Catching On Fire.mp4

# POwer

Just a video to show students what could happen if all energy all at once entered your phone

Practicals

### Practical

A step to demonstrate power - students mass and gravitational energy on the step are calculated. Then a given time jwill calculate his power. (Two steps works well for the most powerful student in the class)