Question

A door 1.6 m wide requires a force of one newton to be applied at the free end to open or close it the force that is required at a point 0.4 m distance from the hinges for opening or closing the door is

Answer 1

In order to open or close the door we required the torque on it

As we can say that torque is the product of force and its distance from the hinge point

$\tau = rF[tex]</p><p>when force is applied at 1.6 m distance then required force F = 1N so </p><p>[tex]\tau = 1* 1.6$

$\tau = 1.6 Nm$

now we applied the force at 0.4 m distance so the required torque must be the same

$\tau = F*0.4$

$1.6 = 0.4*F$

$F = 4 N$

so we required 4 N force on that distance