Problems
Short Answer
Definitions
Simple machines
Everything else
100
A 300-watt engine and a 100-watt electric motor both do 1J of work, which engine can do the work faster?
What is W=Pxt, 1=300xt, t=1/300seconds or 1=100xt, t=1/100seconds...The engine does the work faster because it takes less time.
100
How do output work and input work relate when a machine works?
What is output force is always smaller than work input.
100
How do you find the mechanical advantage?
What is a ratio of output force to input force
100
Which simple machines are described: an inclined plane with one or two sloping sides and an inclined plane wrapped around a cylinder post?
What is a wedge and a screw.
100
A machine that changes ONLY the direction of of a force has a mechanical advantage of what?
What is 1
200
If you use 300N of force to push a rock 15m, how much work did you do?
What is W=fxd, 300Nx15m=4,500 Joules
200
What is work?
What is work is the amount of force applied to an object times the distance the object is moved (in the same direction).
200
What is the SI unit of a joule?
What is one newton times one meter
200
A winding mountain road is an example of what kind of simple machine?
What is inclined plane
200
What are the following simple machines: doorknobs, a bar that pivots about a fixed point, a slanted surface that raises objects?
What is wheel and axle, lever, and inclined plane
300
How much power is needed to do 100J of work on a weight if it takes 20s to lift it?
What is P=W/t, 100/20 = 5Watts
300
How are work, time and power related?
What is Power=work done in a certain amount of time
300
What has an efficiency rate of 100%?
What is an ideal machine
300
A lever with a mechanical advantage greater than 1 is used to do what to the force?
What is increase the force.
300
Which directions of motion can a force perform work?
What is force has to be in the same or opposite direction as the motion.
400
How much work is done if 20W of power is used over 10min?
What is W=Pxt, 20x10x60(must be in seconds) = 12,000J
400
Give an example of a compound machine and ALL the simple machines that make it up.
What is (example) a lawnmower is made up of a lever, wheel and axle, and wedge.
400
What is the pivot point of a lever called?
What is a fulcrum
400
Which of the following simple machines is NOT the same as the others: lever, pulley, wedge, wheel and axle.
What is wedge
400
How do you find the mechanical advantage of a wheel and axle?
What is take the radius of the wheel divided by the radius of the axle.
500
A gardener uses a shovel to move a rock. The rock has a resistance of 3,000N and the gardener applies a force of 300N. What is the mechanical advantage of the shovel?
What is MA=resistance force/force = 3000N/300N=10
500
How is energy transferred during work?
What is when you lift an object you increase its potential energy and then when it moves it has kinetic energy. As you perform work, energy is transferred from you to the object you are working on.
500
What is a compound machine?
What is a machine made of several simple machines
500
List the 6 types of simple machines and state which of the examples is which: knife, flagpole, rake, ramp, wheel, water bottle lid
What is knife - wedge, flagpole - pulley, rake - lever, ramp - inclined plane, wheel - wheel and axle, water bottle lid - screw,
500
A fixed single pulley that lifts a block changes what (direction or force) and how?
What is makes the block easier to lift by changing the direction of the force needed to lift it.
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