A person is lifting a heavy box using a lever. What is the purpose of the lever in this situation?(1 point)

to reduce the force needed to lift the box while keeping the direction of the force the same.

In which situation did a car achieve the greatest efficiency? (Let's assume the cars all have the same mass.)(1 point)

Responses

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.
a car that traveled 90 kilometers on 6.0 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 70 kilometers in 5.0 liters of gas.

a car that traveled 80 kilometers on 5.0 liters of gas.

Which machine has the highest efficiency?

(1 point)
Responses

machine D
machine D

machine B
machine B

machine C
machine C

machine A

The response options are not complete enough to provide a definitive answer. In order to determine which machine has the highest efficiency, we would need more information about the specifics of each machine's input and output. It would require information about the work done by each machine, the energy input, and the energy output. Without this information, it is not possible to determine the machine with the highest efficiency.

How does a pulley make work easier when it is used to lift an object?(1 point)

Responses

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 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 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

Use a stiffer lever to reduce energy lost bending the lever.
Use a stiffer lever to reduce energy lost bending the lever.

Have more than one person help lift the lever.
Have more than one person help lift the lever.

Use it with a lighter load to make it easier.
Use it with a lighter load to make it easier.

Make a longer lever that will require less force.
Make a longer lever that will require less force.

Make a longer lever that will require less force.