Work
Power
Machines
Simple Machines
Vocabulary
100
What is work?
When a force causes an object to move in the same direction as the force.
100
How do you calculate power?
P = W / t
100
What are the two things a machine can do?
Change the size or direction of a force.
100
What is the point at which a lever pivots called?
Fulcrum
100
What is a simple machine that has a grooved wheel with a rope or cable?
Pulley
200
What are the units for work?
Joules (J)
200
What are the units for power?
Watts (W)
200
In your own words, what is the difference between work input and output?
Input is what you do and output is what the machine does.
200
How do you calculate the mechanical advantage of a block and tackle pulley?
Count the number of rope segments.
200
What is a pair of inclined planes that move?
Wedge.
300
Do you do work any time you use force? Explain.
No
300
What is another name for the work done on an object?
Energy
300
What are the units for mechanical advantage?
No units.
300
What has better efficiency, a simple machine or a compound machine? Why?
Simple machine because a compound machine has more friction from the moving parts.
300
What is the ratio of work output to work input of a machine?
Mechanical Efficiency
400
Why is it the same work to get to the top of a mountain if you walk up the slope or climb the cliff?
Force and distance change in opposite directions.
400
Which would require more energy, cutting a board by hand or using an electric saw?
The energy is the same.
400
What is a machine that has 100% efficiency called?
Ideal Machine
400
What does radius mean?
HALF the distance across a circle (wheel or axle)
400
What is the energy of a moving object?
Kinetic Energy
500
Is it more work to lift a 50 N box 0.5 m or to carry a 20 N box 8 m? (You must give a reason, you can't just guess to get the points!)
Lift the 50 N box because you aren't doing work when you carry the 20 N box.
500
Explain the difference between work and power. (DO NOT JUST TELL ME DEFINITIONS)
Power is affected by time.
500
Why is it impossible to create an ideal machine?
Moving parts cause friction.
500
What are the six simple machines? Give an example of each.
Lever, screw, inclined plane, wedge, pulley, and wheel & axle.
500
What is the number of times a machine multiplies force?
Mechanical Advantage
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