Question

Explain why scissors for cutting cloth may have blades longer than the handles, but shears for cutting metals have short blades and long handles. Also mention the class of lever it belongs to and their corresponding mechanical advantages. $\left[5\text{marks}\right]$

Answer 1

A pair of scissors that is used to cut a piece of cloth has blades longer than the handles so that the blades move longer on the cloth when the handles are moved a little. It belongs to the class $\text{I}$ lever as the fulcrum lies in between the load and the effort and since the effort arm is smaller than the load arm so the mechanical advantage is less than $1$.
$\left[2.5\text{marks}\right]$

Shears used for cutting metals have short blades and long handles because it enables us to overcome large resistive force by a small effort. It also belongs to the class $\text{I}$ lever as the fulcrum lies in between the load and the effort and since the effort arm is greater than the load arm so the mechanical advantage is greater than $1$.
$\left[2.5\text{marks}\right]$