Exercise 7.12
Why do you push an object closer to scissors fulcrum when you want to cut an object which is hard?
Not cross-checked
NCERT prints no numerical answer for this exercise, so this working has not been cross-checked against the book.
To make the load arm as short as possible, which raises the mechanical advantage and gives a bigger cutting force.
Scissors are a Class I lever (Table $\displaystyle 7.2$): the screw is the fulcrum, your fingers supply the effort at the handles, the object is the load between the blades.
The balance condition is \(\displaystyle \text{effort} \times \text{effort arm} = \text{load} \times \text{load arm} \) (Eq. $\displaystyle 7.15$), so \(\displaystyle \text{load} = \text{effort} \times \dfrac{\text{effort arm}}{\text{load arm}} \).
Pushing the object close to the fulcrum makes the load arm small, so that ratio is large and the same squeeze of your fingers delivers a much larger force on the object.
Near the tips of the blades the load arm is long, the force is small, and a hard object will not cut.