Give an example of a 1st class lever, 2nd class lever, and 3rd class lever found in the real world.
The correct answer and explanation is:
Correct Answer:
- 1st class lever: Seesaw
- 2nd class lever: Wheelbarrow
- 3rd class lever: Human forearm when lifting a weight
Explanation:
Levers are simple machines that consist of a rigid bar that rotates around a fixed point called the fulcrum. They are classified into three types based on the relative positions of the effort, load, and fulcrum.
A 1st class lever has the fulcrum positioned between the effort and the load. A seesaw is a classic example. When one person sits on one end and another person pushes down on the other end, the board pivots around the center. The fulcrum is in the middle, the load is on one side, and the effort is applied on the opposite side. This type of lever can provide a balance between force and speed, depending on the distances of the effort and load from the fulcrum.
A 2nd class lever has the load positioned between the effort and the fulcrum. A wheelbarrow demonstrates this type of lever. When lifting the handles of a wheelbarrow, the wheel acts as the fulcrum at the front, the load sits in the middle container, and the effort is applied by lifting the handles. This design provides a mechanical advantage because the effort arm is longer than the load arm, making it easier to lift heavy objects with less force.
A 3rd class lever places the effort between the load and the fulcrum. A common example is the human forearm when lifting a dumbbell. The elbow acts as the fulcrum, the biceps apply the effort in the middle of the forearm, and the load is the weight held in the hand. This type of lever does not provide a mechanical advantage in terms of force, but it allows for greater speed and range of motion, which is important in many human movements.