Why a force is applied at right angles to the heavy door at the outer edge while closing or opening it?

Why a force is applied at right angles to the heavy door at the outer

1.	Why a force is applied at right angles to the heavy door at the outer edge while closing or opening it?
Answer» Solution :TORQUE `tau=F R SIN theta` For a force applied at right ANGLE to the OUTER edge of the door i.e. `theta=90^(@) :' sin 90^(@)=1` `:. tau=Fr` `:.` The values of `sin theta` and r are maximum. So, torque produced is maximum. Hence force is applied at right angles to the heavy door at the outer edge.