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41 Cards in this Set
- Front
- Back
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What is the formula for a joule?
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A joule equals one newton x one meter
(N x m) |
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What is the result of a force moving an object over a distance?
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Work
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What are you doing when you push, lift, or throw and object?
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Work
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What is the formula for work?
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W = F x D
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What is "F" ?
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F = force acting on an object
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What is "d"?
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d = distance the object moves in the direction of the force
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What is the unit of measurement for work in the metric system?
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Joule
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A joule equals the force of what?
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A newton moving an object 1 meter
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Who is the joule named after?
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James Prescott Joule
19th century English physicist who studied transformation |
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What is the work done when a 500-N student climbs a rope for 5 meters?
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W = F x D
W = 500n x 5m W = 2500 x m W = 2500J |
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Is a horse doing work when it stands with a rider sitting on it?
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No - because the horse is not pushing, lifting, or throwing. No force is acting over a distance.
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When you climb to the top of rope and hang there, are you doing work?
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No - not moving your body over a distance
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What is the amount of work done during a given period of time
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Power
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How is power measured?
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Power is measured in watts (W)
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A watt is equal to how many joule?
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1 W = joule per second
(J/s) |
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How many joules is a 100W lightbulb using?
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100 joules per second
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A kilowatt (kW) is equal to how many watts?
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1 kW = 1000 W
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One horsepower is equal to how many watts?
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1 hp = 0.746W
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Horsepower is used to describe what?
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The power of engines
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Who described the power of a steam engine?
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James Watt
A Scottish engineer described the power used to a horse to pull a heavy load |
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What is the equation of power?
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Power = Work/Time
P = w/t |
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What is the power of a motor that does 2000 J of work in a 10 second period?
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P = w/t
P = 2000J/10s P = 200J/S P = 200W |
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If the power of a motor is 200W, what is the horsepower of the motor?
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200W / 746W = .26hp
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Is throwing a football 20 yards work or not?
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Yes
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You push against a wall until you are tired. Is this work?
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No
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Your study these flashcards all day long for this stupid test. Is this work?
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No
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You push your brother out of your way to sit down - are you working?
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Yes
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How much work is done when a 175 N man pulls a sled 500m?
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W = F x D
W = 175 x 500 W = 87,500J |
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A 98 N woman carries her baby 12 m. How much work is done?
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No work
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What is the work done when a 1000-N person jumps 1 meter into the air?
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W = F x D
W = 1000 N x 1m W = 1000 x m W = 1000J |
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A 100W lightbulb has more what than a 60W bulb?
a. power b. joule c. watt d. force |
Power
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What is the amount of work per unit of time?
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Power
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What is the reate at which work is done?
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Power
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When power increases, does the rate of work increase or decrease
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Increase
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How much work does a 150w lightbulb do?
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150 joules
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Power is force x distance and divided by what?
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Time
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When time and force remain the same, power is increased when what increases?
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Distance
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What is the equation for power?
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P = Work/Time
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Power is measured in what?
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watts
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One horsepower equals how many watts?
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746 watts
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A pencil sharpener uses 1,000 joules in 10 seconds. What is the power usage?
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P = 1,000j /10s
P = 100j / s P = 100W |
