Which lever class places the axis between the input and output with opposing sides?

Which lever class places the axis between the input and output with opposing sides?

• A. Second class lever
• B. First class lever
• C. Third class lever
• D. None of the above

Answer: (B)

The key idea is how the pivot (fulcrum) is placed relative to where you apply effort and what you move. When the pivot sits between the input force and the output load, with those two forces on opposite sides of the pivot, you’re looking at a first class lever. A classic example is a seesaw, where pushing down on one side causes the other side to rise with the pivot in the middle. This arrangement exactly matches the description of the axis between input and output on opposing sides, which is why it’s the best answer. In the other two setups, the load sits between the pivot and the effort, or the effort sits between the pivot and the load, so the pivot is not between input and output.

The key idea is how the pivot (fulcrum) is placed relative to where you apply effort and what you move. When the pivot sits between the input force and the output load, with those two forces on opposite sides of the pivot, you’re looking at a first class lever. A classic example is a seesaw, where pushing down on one side causes the other side to rise with the pivot in the middle. This arrangement exactly matches the description of the axis between input and output on opposing sides, which is why it’s the best answer. In the other two setups, the load sits between the pivot and the effort, or the effort sits between the pivot and the load, so the pivot is not between input and output.