p h y s i c s introduction to work, power & kinetic energy
TRANSCRIPT
Work
Work is done when a force acts parallel to the direction of the displacement
Fo
rce
Displacement
Dis
pla
cem
ent
Force
Work
Work is done when a force acts parallel to the direction of the displacement
Air Resistance
Force
Displacement
Dis
pla
cem
ent
Friction Force
Work or Not?
Man holds out heavy concrete block at arm’s length for 10 minutes
Student pushes car down street Women holds up a large box over-head while
walking down the hall way Child pushes a cart along the side walk
WORK
WORK
NOT WORK
NOT WORK
Work-Energy Theorem
Work done on an object is equal to its change in kinetic energy
W = ∆KEW work (J)
∆KE change in kinetic energy (J)
Note:
Household Appliances 60W light bulb - 60W Toaster : 800-1500W Microwave : 600-1500W Dishwasher : 1200-1500W Washing Machine : 500W Vacuum Cleaner : 200-700W Clothes dryer : 4000W Ceiling Fan : 10-50W Hair Blow dryer : 1000W Laptop Computer : 20-50W Desktop Computer : 80-150W Cell Phone Charger: 3-5W iPod/iPad Charger: 10W
Time to explore Power
What do we need to know to calculate power?
What is your force? So if 1lb=2.2kg how much mass do
you have? How can we calculate velocity?