Question

Write an expression for the mechanical advantage of a lever.

Answer 1

Levers:

1. It is the simplest and most common machine used in everyday life.
2. A lever is a rigid, straight or bent bar capable of rotating around a fixed point or its axis called the fulcrum.
3. A fulcrum (F) does not move but remains fixed when a lever is in use.

Principle of a lever and expression of mechanical advantage:

1. According to the principle of moments, in the equilibrium position of the lever,

$$\begin{gathered} Momentofloadaboutthefulcrum=Momentofeffortaboutthefulcrum \\ Load\times Loadarm=Effort\times Effortarm \\ \frac{Load}{Effort}=\frac{Effortarm}{Loadarm} \\ MechanicalAdvantage\left(MA\right)=\frac{Effortarm}{Loadarm} \end{gathered}$$

2. This expression is known as the law levers.

3. The MA of a lever is equal to the ratio of the length of its effort arm to the length of its load arm.

Conditions to change Mechanical advantage:

1. $effortarm=loadarm,thenMA=1$
2. $effortarm<loadarm,thenMA<1$
3. $effortarm>loadarm,thenMA>1$
4. Thus, to increase the MA of a lever, either the effort arm should be increased or the load arm should be decreased.