Question

A moment of $200\text{N-m}$ required to open the door. Determine the distance of the point of force from the hinged point if a $50\text{N}$ force perpendicular to the radius can just open the door.

• A. $3\text{m}$
• B. $1\text{m}$
• C. $4\text{m}$
• D. $2\text{m}$

Answer 1

The correct option is C $4\text{m}$

Given:
Force applied, $F=50\text{N}$
Moment of force, $\tau =200\text{N-m}$

Let the distance of the point of application of force be at a distance $d$.
From definition of moment of force,
$\tau =F\times d$
$d=\frac{\tau }{F}$
$d=\frac{200\text{N-m}}{50\text{N}}$
$d=4\text{m}$