Use the image of a person lifting a boulder with a lever to answer the question.
An illustration shows a man using a stick and a small rock as a lever to lift a large rock.
Where is the fulcrum in this situation?
(1 point)
Responses
It is the point where the person’s hands push down on the bar.
It is the point where the person’s hands push down on the bar.
It is the point where the bar touches the boulder.
It is the point where the bar touches the boulder.
It is the point where the boulder touches the ground.
It is the point where the boulder touches the ground.
It is the point where the bar touches the smaller rock.
11 answers
It is the point where the bar touches the smaller rock.
In which situation did the car achieve the greatest efficiency? (Assume the cars all have the same mass.)(1 point)
Responses
a car that traveled 70 kilometers on 5.0 liters of gas
a car that traveled 70 kilometers on 5.0 liters of gas
a car that traveled 50 kilometers on 4.0 liters of gas
a car that traveled 50 kilometers on 4.0 liters of gas
a car that traveled 80 kilometers on 5.0 liters of gas
a car that traveled 80 kilometers on 5.0 liters of gas
a car that traveled 90 kilometers on 6.0 liters of gas
Responses
a car that traveled 70 kilometers on 5.0 liters of gas
a car that traveled 70 kilometers on 5.0 liters of gas
a car that traveled 50 kilometers on 4.0 liters of gas
a car that traveled 50 kilometers on 4.0 liters of gas
a car that traveled 80 kilometers on 5.0 liters of gas
a car that traveled 80 kilometers on 5.0 liters of gas
a car that traveled 90 kilometers on 6.0 liters of gas
The car that traveled 80 kilometers on 5.0 liters of gas achieved the greatest efficiency.
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 B
machine B
machine D
machine D
machine A
machine A
machine C
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 B
machine B
machine D
machine D
machine A
machine A
machine C
Machine C has the highest efficiency.
How does a pulley make work easier when it is used to lift an object?(1 point)
Responses
It changes the direction of the lifting force to work with gravity.
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.
It decreases the distance over which the force must be applied to lift the object.
It reduces the weight of the object being lifted.
It reduces the weight of the object being lifted.
It increases the amount of work produced to lift the object.
Responses
It changes the direction of the lifting force to work with gravity.
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.
It decreases the distance over which the force must be applied to lift the object.
It reduces the weight of the object being lifted.
It reduces the weight of the object being lifted.
It increases the amount of work produced to lift the object.
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
Use a stiffer lever to reduce energy lost bending the lever.
Use a stiffer lever to reduce energy lost bending the lever.
Use it with a lighter load to make it easier.
Use it with a lighter load to make it easier.
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.
Responses
Use a stiffer lever to reduce energy lost bending the lever.
Use a stiffer lever to reduce energy lost bending the lever.
Use it with a lighter load to make it easier.
Use it with a lighter load to make it easier.
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.
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%
80%
80%
24%
24%
60%
Responses
32%
32%
80%
80%
24%
24%
60%
The efficiency of the ramp is 60%.
Efficiency = (Useful energy output / Energy input) x 100
Efficiency = (1200 / 2000) x 100
Efficiency = 0.6 x 100
Efficiency = 60%
Efficiency = (Useful energy output / Energy input) x 100
Efficiency = (1200 / 2000) x 100
Efficiency = 0.6 x 100
Efficiency = 60%
6 answers