A lever is a first-class lever when:

A lever is a first-class lever when:

• A. The fulcrum is between the input force and the load
• B. The load is between the input force and the fulcrum
• C. The input force is between the load and the fulcrum
• D. The fulcrum is at one end of the lever

Answer: (A)

The key idea is how the lever is arranged around the pivot. A first-class lever has the fulcrum between the effort (input force) and the load. This setup lets you balance torques on opposite sides of the pivot and adjust either the force required or the speed of movement by changing the distances from the fulcrum. For example, on a seesaw, the pivot sits between the two sides. If you move farther from the fulcrum on one side, you can lift a heavier load on the other side with less force, or you can balance with equal effort if the distances are right. If the load is between the pivot and the effort, that’s a second-class lever. If the effort is between the pivot and the load, that’s a third-class lever. If the fulcrum is at an end, it doesn’t fit the first-class arrangement.

The key idea is how the lever is arranged around the pivot. A first-class lever has the fulcrum between the effort (input force) and the load. This setup lets you balance torques on opposite sides of the pivot and adjust either the force required or the speed of movement by changing the distances from the fulcrum.

For example, on a seesaw, the pivot sits between the two sides. If you move farther from the fulcrum on one side, you can lift a heavier load on the other side with less force, or you can balance with equal effort if the distances are right.

If the load is between the pivot and the effort, that’s a second-class lever. If the effort is between the pivot and the load, that’s a third-class lever. If the fulcrum is at an end, it doesn’t fit the first-class arrangement.