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46 Cards in this Set
- Front
- Back
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Work is
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force applied over a distance (change in position)
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Effort (force) does not guarantee ___________
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work
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Why is pushing on a wall not work?
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You do not change its position
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Distance moved does not guarantee _________
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work
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Why is puck sliding on ice no work?
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it does not require a force to move it
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What is works formula?
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work=force*distance
w=fd |
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What is the work if the force is 20N and distance is 5 meter
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20*5=100N-M
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What is the unit for work?
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joule(N-M)
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Simple machines _____________________________
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make work easier
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List 3 ways simple machines make work easier.
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1.increase the force
2.change direction force 3.change speed of force |
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Machine cannot ________________________
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increase the amount of work done
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A _______________is a fixed rigid bar turning on a fixed point called the _____________
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lever
fulcrum |
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Lever balances ________________________
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measured merchandise
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Proverbs II
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warn against false balance
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Law of Moments
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This work on a balanced lever
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What is the formula for the Law of moments
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w1d1=w2d2
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find the distance when 300N are applied and when 450N are applied it is moved 1m
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300Nd1=450N(1m)
d1=450N-M/300N d1=1.5m |
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List the 3 types of levers
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1st Class Lever
2nd Class Lever 3rd Class Lever |
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Describe 1st Class Lever
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Fulcrum between the effort and resistance
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Describe 2nd Class Lever
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resistance between the fulcrum and effort
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Describe 3rd Class Lever
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effort between the fulcrum and resistance
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What is the distance principle?
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less effort means you cover more distance
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What is the mechanical advantage?
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"force multiplying" ability of a machine
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MA=
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resistance force divided by effort force
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What is the formula for mechanical advantage
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MA=Fr/Fe
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What is the mechanical advantage if resistance force is 100N and effort force is 35N
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MA=100N/35N
MA=2.8 |
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Describe a wheel and axle
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A lever modified to cover distance
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Give and example of a wheel and axle
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bicycle
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Describe how effort is provided
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feet provide effort which is transferred to the wheel by the sproket, chain, and axle
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List 2 types of pulleys
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single fixed pulley
single moveable pulley |
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Describe single fixed pulley
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ma=1
change direction of force |
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Describe single movable pulley
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MA=2 because pulley moves in direction of effort force
Pull twice as much rope |
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Describe the Block and Tackle
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An arrangement of multiple fixed and movable pulleys
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How do you figure MA in BLock and Tackle
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count the ropes except the one you pull on
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What is the MA of a piano 2400N being raised with 7 ropes
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MA=2400/6=400
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List the three points of the Distance Priciple
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1.If it takes less effort, you will have to move a bigger distance
2. If it moves a smaller distance, you will have to use more force. 3. |
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Describe Incline Planes
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A ramp that spreads the fource out over a longer distance
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How much work do you do when you lift a 6000N rock 32m up?
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6000*32=192,000J
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Describe Idealization
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All machines ignore friction
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In the real world, you put more _______ in than you get out because you have to work to overcome __________
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work
friction |
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Efficiency=
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who + percent of work is used to move(the other ?% is used to overcome friction)
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Describe Wedges
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2 inclined planes placed bottom to bottom - help cut through object
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Describe screw
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an inclined plane wrapped around a cylinder or a cone - hold things together
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define power
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the rate (how fast) of doing work
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power=
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work/time
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What is the power if a man performs 200J of work in 10 second
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Power=work/time
power=200J/10sec Power=20J/sec |
