1. Power

2. What is power? Definition: The SI unit for power is the watt (W)
A measure of the amount of work that can be done in a given amount of time
The SI unit for power is the watt (W)
What are some common places where you see power labeled in everyday life?
What is power?

3. Calculating Power W P t Power can be represented by the equation:
W = Work measured in Joules (J)
t = Time measured in seconds (s)
Calculating Power W P t

4. Practice Calculating Power from Work and Time
A microwave oven does 24,000 J of work in 30 seconds. What is the power of the microwave?
P = ?
W = 24,000 J
t = 30 sec
24000J/30sec = 800 J/s OR 800 W
Calculating Work from Power and Time
If you use a 1000 watt microwave oven for 20 seconds, how much work does it do?
P = 1000 W
t = 20 sec
W = ?
1000 W x 20 sec = 20,000 J
Practice

5. A machine does 1,500 J of work in 30 seconds
A machine does 1,500 J of work in 30 seconds. What is the power of this machine?
A horse moves a sleigh 1 km by applying a 2,000 N force on its harness for 45 min. What is the power of the horse?
Suppose a force of 100 N is used to push an object a distance of 5.0 m in 15 seconds. How much power was used?
Even More Practice!