Question

What are examples of $1^{st}$ , $2^{nd}$ and $3^{rd}$ class levers?

Answer 1

Hint: To answer this question, we first need to understand what are levers. A lever is a simple mechanism made up of a beam or rigid rod that pivots around a fixed fulcrum. A lever is a stiff body that can rotate around a central axis. The lever is classified into three categories based on the fulcrum, load, and effort positions.

Complete step by step solution:
First class lever - The fulcrum is between the effort (force) and the load in a first-class lever, and the effort (force) moves over a big distance to move the load a lesser distance. The mechanical advantage of a first-class lever grows as the ratio of effort (force) arm length to load arm length grows.
Second class lever – In a second-class lever, the effort is distributed over a vast area in order to lift the load a short distance. The mechanical advantage of a second-class lever grows as the ratio of effort (force) arm length to load arm length grows. The larger the mechanical advantage in a wheelbarrow, the closer the load is to the wheel. Another example of a second-class lever is a nutcracker.
Third class lever – The load moves further than the effort (force) in a third-class lever, and the mechanical advantage is minimal, making it difficult to deliver significant force to the load. When you use your forearm to raise a load, you're using a third-class lever. Just in front of the elbow, your biceps muscles are joined to the forearm. The effort is split between the fulcrum (elbow) and the load, with the load on the hand.
So, we conclude that the examples of
$1^{st}$ class levers; Fulcrum in the middle; Triceps extension at the elbow.
$2^{nd}$ class levers; Load in the middle; Ankle joint (plantar flexion)
$3^{rd}$ class levers; Effort in the middle; Bicep curl (flexion at elbow)

Note:
The lever mechanism was first discovered in the ancient Near East around 5000 BC. The first horizontal frame loom was powered by a foot pedal. The shadow, a crane-like contraption with a lever mechanism, was invented in Mesopotamia (now Iraq) in 3000 BC. Workmen in ancient Egypt utilized the lever to raise and move obelisks weighing more than 100 tones.