Question

How do you calculate the mechanical advantage of a second-class lever?

Answer 1

Hint: This is a different kind of question, where from the definition of mechanical advantage, the formula for the mechanical advantage of a second-class lever can be found. To find the formula, first understand what mechanical advantage is and how the mechanical advantage of a lever can be calculated. Once this is clear, then calculating the mechanical advantage of a second-class lever becomes easy.

Formula used:
$\dfrac{E}{L}=\dfrac{b}{a}$

Complete solution:
We know that the mechanical advantage is given by the below formula:
$\text{Mechanical}\,\text{Advantage}\,=\,{\text{Force on the load}}/{\text{Force you exert}}\;$

This is usually called the “actual” mechanical advantage. The ideal mechanical advantage is often used to estimate an expected value for the advantage. It is based on the distances moved by the load and the user.

The mechanical advantage of a second-class lever is given by Effort – Load – Fulcrum formula, which can be written as:
$\dfrac{E}{L}=\dfrac{b}{a}$
where,
$\begin{align}
  & E\,:\,\text{Effort} \\
 & L\,:\,\text{Load} \\
 & a\,:\,\text{Distance between Effort and Fulcrum} \\
 & b\,:\,\text{Distance between Load and Fulcrum} \\
\end{align}$

Therefore, $E\,.\,a=L\,.\,b$ is the formula that can be used to calculate the mechanical advantage of a second-class lever.

Additional Information:
A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. A lever is a rigid body capable of rotating on a point on itself. Based on the locations of fulcrum, load and effort, the lever is divided into three types.

Also, a leverage is a mechanical advantage gained in a mechanical system. It is one of the six simple machines identified by Renaissance scientists. A lever amplifies an input force to provide a greater output force, which is said to provide leverage.

The ratio of the output force to the input force is the mechanical advantage of the lever. As such, the lever is a mechanical advantage device, trading off force against movement.

Note:
This type of question is rarely asked in exams, as these questions are little complex to solve and maximum time the student fails to get the answer for this question. The formula of mechanical advantage is very important to get the answer for this question, along with the terms on which the second-class lever depends.