WORK AND POWER : WORK AND POWER By:
Kevin Yu What is Work? : What is Work? Work is the amount of energy transferred by a force acting through a distance.
Work is done when a force produces motion.
Work is a scalar quantity.
Joules are the standard units for Work. W= Fd Slide 3: What is Power? Power is the rate at which work is performed or energy is converted.
The standard unit for power is Watts, which is equal to one joule per second. P = W/t = Fd/t Slide 4: John and Zombie X run a distance of 100 meters. John is running with a force of 300N. And Zombie X is running with a force of 600N. Which of the two does more work? 300N 600N John Loses : John Loses John W = Fd
W = (300N)(100m)
W = 30000J Zombie X W = Fd
W = (600N)(100m)
W = 60000J Slide 6: If John lifted a box weighing 500N to a height of 8 meters in 10 seconds and Zombie X lifted a box weighing 250N to a height of 4 meters in 5 seconds, who exerts more power? John wins : John wins John P = W/t = Fd/t
P = Fd/t
P = (500N)(8m) / (10s)
P = 4000J / 10s
P = 400W Zombie X P = W/t = Fd/t
P = Fd/t
P = (250N)(4m) / (5s)
P = 1000J / 5s
P = 200W Need help remembering units? : W=Joules
Work=Fd That equation won’t help much to remember the units.
Instead think of W=Total Change in Energy. Showing that Joules is the unit of measure. For Power think of“I’m going to turn the power on.”
Think of turning on a light bulb which is measured in Watts. Need help remembering units? http://videos.howstuffworks.com/hsw/17434-physics-calculating-work-and-power-video.htm : http://videos.howstuffworks.com/hsw/17434-physics-calculating-work-and-power-video.htm Homework Problem : Homework Problem