Answer:
to reduce the <em>force</em> needed to lift the box and <em>change</em> the direction of the force
Explanation:
1. "A lever consists of a rigid bar that is able to pivot at one point. This point of rotation is known as the fulcrum. A force is applied at some point away from the fulcrum (typically called the effort)."
By this definition, we know that force is needed to lift an object using a lever.
2.<u> "When the input and output forces are on opposite sides of the fulcrum, </u><u>the lever changes the direction of the applied force.</u> This occurs only with first-class levers. When both the input and output forces are on the same side of the fulcrum, the direction of the applied force does not change"
For example, on a sew saw, if a force is applied on one end, you on the other side/end would go up, meaning <u>a change in direction</u>.
3. Lastly, we know <u><em>a lever is typically used to reduce work</em></u>, in other words, the force needed to move something.
Basically, if we were to put a lever into an equation:
reduced force + change in direction = lever
(<em>the expection</em>) <u>unless load and force are on the same side</u>, there will be <u>no change in direction. </u>
For example, if you and your friend sit on the same side of a sew saw, the sew saw would not go up or down, meaning no change in direction.
So if not stated otherwise you can assume the load and force are on opposite sides. The purpose of a lever in that situation would be to reduce the force needed to lift the box and change the direction of the force.
*While reading my explanation, it may be helpful to look up a diagram containing a lever, with a load, fulcrum, and applied force.
