Use the table to answer the question.
Machine Output Work (J) Input Work (J)
A 750 1,500
B 1,000 4,000
C 450 600
D 3,000 5,000
Which machine has the highest efficiency?
(1 point)
Responses
machine D
machine D
machine A
machine A
machine B
machine B
machine C
machine D
How does a pulley make work easier when it is used to lift an object?(1 point)
Responses
It decreases the distance over which the force must be applied to lift the object.
It decreases the distance over which the force must be applied to lift the object.
It increases the amount of work produced to lift the object.
It increases the amount of work produced to lift the object.
It reduces the weight of the object being lifted.
It reduces the weight of the object being lifted.
It changes the direction of the lifting force to work with gravity.
It decreases the distance over which the force must be applied to lift the object.
A certain lever system is only 30% efficient. What could make it more efficient? (1 point)
Responses
Have more than one person help to lift the lever.
Have more than one person help to lift the lever.
Make a longer lever that will require less force.
Make a longer lever that will require less force.
Use it with a lighter load to make it easier.
Use it with a lighter load to make it easier.
Use a stiffer lever to reduce energy lost bending the lever.
Use a stiffer lever to reduce energy lost bending the lever.
Use a stiffer lever to reduce energy lost bending the lever.
What is the efficiency of a ramp if 2,000 joules of energy results in 1,200 joules of work?(1 point)
Responses
32%
32%
24%
24%
60%
60%
80%
80%