Jack notices a seesaw in the playground and decides to lift his friend sitting on one end. He struggles initially but then shifts his position. What concept of the lever is Jack applying, and how does it help him lift his friend?

Answer: D. Moving farther from the pivot point reduces effort by increasing the distance over which the force is applied.

Jack is applying the concept of torque (moment of force) in a Class 1 Lever. In a lever, the Effort Arm is the distance between the person (the effort) and the pivot (the fulcrum). By moving farther from the pivot, Jack increases the length of the effort arm. A longer distance allows him to apply the same amount of force to create a much greater turning effect, thereby reducing the physical effort needed to lift his friend.

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