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Work & Power. Work. For work to occur two things must happen: The object has to move some distance. The object has to move in the same direction as the applied force – only the force acting IN THE SAME DIRECTION as the object’s motion is performing work. Calculating Work.
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Work • For work to occur two things must happen: • The object has to move some distance. • The object has to move in the same direction as the applied force – only the force acting IN THE SAME DIRECTION as the object’s motion is performing work.
CalculatingWork • The amount of work done depends on BOTH the AMOUNT OF FORCE exerted and the DISTANCE THE OBJECT MOVES. • The amount of work can be determined by multiplying FORCE times DISTANCE: Formula: W = (F)(d) W = work F = Force d = Distance
Calculating Work • SI Unit of Work = • When force = NEWTONS (N) • When distance = METERS • Joule (N*m) • Named after James Prescott Joule an physicist from the mid 1800’s who studied work • 1 Joule =1 Newton of force to move an object 1 meter • Joule is abbreviated with as J
- What Is Work? The Meaning of Work • Work is done on an object when the object moves in the same direction in which the force is exerted.
Power • Work is UNAFFECTED BY TIME • Power is the rate (time) at which work is done. • how fast or slow work is done • Power equals the amount of work done on an object in a unit of time. • With more power you can do the same amount of work in less time.
Calculating Power • Formula to calculate power: Power = Work Time OR Power = force x distance Time
When work is measured in joules, and time in seconds: • SI Units for power: Joule/second (J/sec) • 1 Watt = Joule/Sec. (J/s) James Watt & His Steam Engine
Units of Power • One watt is a small amount of power • Power is more often expressed in KILOWATT • Kilowatt = 1000 watts • Horsepower: English Unit (not an SI unit) • 1 HP = 746 Watts Corvette
Question Answer Quick Summary: Work is done when an object moves in the same direction in which the force is exerted. What is work? How can you calculate work? Work = Force X Distance Power is the rate at which work is done. P = work / time What is power?