Question

A foolish boy remove a nail from a vertical wall by pulling a stick attached to the nail in a direction 30 deg to the wall.
if the tension in the stick is 10cm , calculate the magnitude of the force wich is not effective in pulling out the nail, is it possible to remove the nali thos way if minimum force required is 7N?
why is the boy foolish?

Answer 1

Magnitude of force which is not effective in pulling out the nail $=10\ cos30\degree= 5\sqrt{}3=8.66\ N$

Effective force for removing the nail= 10 - 8.66

= 1.34 N

So,

He will not be able to pull the nail

He is foolish because he should have tried to pull the nail by applying the force perpendicular to wall