POWER

=Power= Power is the rate at which work is done (or energy is transformed). It can be measured as the amount of work done (energy transformed) per second. ===[image:http://i.imgur.com/bwkX3kf.png]=== === ==='''P''' (Power), '''W''' (Work) and '''t''' (Time) Power is measured in Watts (W). A device that is rated 1 kW uses 1000 Joules of energy per second. The equation for Power can be put into a triangle as follows: [image:http://i.imgur.com/wJkdH87.png] ==Examples== [image:http://i.imgur.com/3gbiFkx.png?1] If a lightbulb uses 3.6 kJ per minute what is its power rating \( P = \frac{W}{t} \) \( P = \frac{3600 (J)}{60 (s)} \) \( P = 60(W) \) We pay for the amount of energy used in the home through our power bill. Appliances have different power ratings, which mean that they use energy at different rates. The cost of running an appliance depends on the rate at which it uses energy and the time it is left running. [image:http://i.imgur.com/sPQEQy1.png?1] If a 1.2 kW microwave is left running for 1 minute, how much energy does it use? \( E = P \times t \) \( E = 1200 (W) \times 60 (s) \) \( E = 72,000 J \) or \( 72 kJ \)