Work And Simple Machines Test (II) Question Preview (ID: 24299)
Unit 8 Review For 8th Grade.
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What two things must happen for work to be done?
a) The object must move and there must be an output force
b) The object must move in the oppostie direction of the force
c) The object must move in the same direction as the force
d) The object must move and the mechanical advantage must be greater than 1
What does a fixed pulley change?
a) the speed of a force
b) the direction of a force
c) the size of a force
d) the timing of the force
If a barbell weighs 160 N, what other information do you need to calculate how much work it takes to lift it?
a) the shape of the weights
b) how high the barbell is being lifted
c) the strength of the person doing the lifting
d) the amount of output force
Which of the following is the comparison of a machine's work output with the work input?
a) mechanical efficiency
b) force
c) mechanical advantage
d) power
What is the work done by a machine on an object?
a) power
b) work input
c) work output
d) lever
What is it called when a force causes an object to move in the direction of the force?
a) energy
b) force
c) work
d) power
How does a ramp make lifting a heavy object easier?
a) The object is moved over a shorter distance
b) The ramp increases the amount of work you do
c) Less force is needed to move the object over a longer distance
d) More force is needed to move the object over a longer distance
A doorknob is an example of a
a) pulley
b) wheel and axle
c) lever
d) screw
What is a device that makes work easier by changing the size or direction of force?
a) power
b) watt
c) machine
d) force
If an identical stack of books is lifted the same distance and one person does the job twice as fast, which of the following is done twice as much?
a) work input
b) work output
c) power
d) efficiency
Chris and Jane are lifting boxes to put them on shelves. Chris does 200 J of work in 5 minutes and Jane does 200 J of work in 4 minutes. What is the difference between the two jobs?
a) the input force
b) the output force
c) the work
d) the power
Which of the following is NOT a wedge?
a) knife
b) plow
c) chisel
d) ramp
What is a machine with a grooved wheel that holds a cable?
a) lever
b) pulley
c) wheel and axle
d) wedge
A construction worker is lifting a load of bricks onto a truck. He does 200 J of work in 40 seconds. What is his power output?
a) 50 J
b) 5 J
c) 50 W
d) 5 W
Which of the following is a compound machine?
a) lever
b) block and tackle pulley
c) wheel and axle
d) screw
Which of the following causes machines not to be 100% efficienct?
a) friction
b) input force
c) output force
d) power
Greg applies a force of 100 N to move a box 5 meters. How much work did he do?
a) 100 J
b) 500 J
c) 5 J
d) 500 N
What is machine that is made of two simple machines?
a) simple machine
b) lever
c) pulley
d) compound machine
What is the work that you do on a machine?
a) power
b) work input
c) work output
d) lever
Force times _______________ is the formula to calculate work.
a) kinetic
b) work
c) distance
d) machines
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