Work and Power. What does work mean to you? In physics, work has a very specific meaning. It is the...
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Transcript of Work and Power. What does work mean to you? In physics, work has a very specific meaning. It is the...
![Page 1: Work and Power. What does work mean to you? In physics, work has a very specific meaning. It is the action to make things change Work= force x distance.](https://reader036.fdocuments.us/reader036/viewer/2022062720/56649f185503460f94c2ebf7/html5/thumbnails/1.jpg)
Work and Power
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What does work mean to you?
![Page 3: Work and Power. What does work mean to you? In physics, work has a very specific meaning. It is the action to make things change Work= force x distance.](https://reader036.fdocuments.us/reader036/viewer/2022062720/56649f185503460f94c2ebf7/html5/thumbnails/3.jpg)
In physics, work has a very specific meaning. It is the action to make things change
Work= force x distance W=F x d
Unit: N-m : Joule
Work
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W = F x d
Therefore:
You must have MOTION in order to have work… something has to change position
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Work = Force x distance
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Work …the motion has to take place parallel to the
direction of the force
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Garcon does work whenhe picks up the trayGarcon does work whenhe picks up the tray
but not while hecarries it around
the room
Garcon is not doing work
Work and Energy…the motion (distance) is parallel to the
direction of the force
![Page 8: Work and Power. What does work mean to you? In physics, work has a very specific meaning. It is the action to make things change Work= force x distance.](https://reader036.fdocuments.us/reader036/viewer/2022062720/56649f185503460f94c2ebf7/html5/thumbnails/8.jpg)
Is Atlas doing work?
NONO
Atlas is staying in place
Atlas is not doing work
![Page 9: Work and Power. What does work mean to you? In physics, work has a very specific meaning. It is the action to make things change Work= force x distance.](https://reader036.fdocuments.us/reader036/viewer/2022062720/56649f185503460f94c2ebf7/html5/thumbnails/9.jpg)
Is work being done on the wall?
work may be done on the prisoner’s muscles …stretching,
squeezing them, pumping the blood through the veins..
but this is not work being done on the wall be clear where the
work goes
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Is work being done?
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Example Problems
How much work is done by a toy car with an applied force of 12 N which is moved for 39 m?
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Power
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Pit Pony
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A little bit of history
To find out how the power of his engine compared to that of a horse, James Watt measured how fast an average horse could do work. He found the answer and expressed the amount of work performed per second as a horsepower.
1 horsepower = 746 WattsA horse exerting 1 horsepower can raise 330
pounds of coal 100 feet in a minute.In the US we rate engines in terms of
horsepower (hP) and electricity in watts (kilowatts, megawatts)
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Horsepower
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PowerPower – the rate at which work is done.
Power = Work/time
Unit is Watt (joule/second)
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ONE OF 2 THINGS
POWER = WORK DONE TIME
2X WORK OR WORK TIME ½ TIME
What can a more powerful engine do?
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Example ProblemsIf a 450 N boulder is dropped 2.4 m in 25 seconds, how much power is exerted on the object?
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The weight lifter used a force of 980 N to raise the barbell over her head in 5.21 seconds. Approximately how much work did she do in raising the barbell?
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A mechanic used a hydraulic lift to raise a 12,054 N car 1.89 m above the floor of a garage. It took 4.75 s to raise the car. What was the power output of the lift?
Example ProblemsExample Problems