Question

Needles have sharp edges

Answer 1

as we know Needles are used to stitch clothes. Also we have noticed that Needles are penetrated inside a cloth to get desired work.
For the above process to be happened needle should have sharp edges, if Needles have blunt edges than force acting per unit area will be less and we have to do more effort in stitching purposes.Making Needles Sharpe edge increases the force acting per unit area.

Hope you get your answer.

Answer 2

FORCE & PRESSURE

√√Needles have sharp edges

>>what is sharp edges ??

>>sharp edges means less area and as pressure is inversely proportional to area, pressure exerted will be more.

>> it means that better the edges we'll have have to apply less afford

hope it helps