Aperson exerts a horizontal force of 42 n on the end of a door 96 cm wide. what is the magnitude of the torque if the force is exerted (a) perpendicular to the door and (b) at a 60.0â° angle to the face of the door?

(a) 40.3 Nm

When a force is applied perpendicular to the door, the magnitude of the torque exerted by the person is given by

where

F = 42 N is the magnitude of the force

d = 96 cm = 0.96 m is the distance between the point of application of the force and the centre of rotation of the door

Substituting numbers into the formula, we find

(b) 34.9 Nm

In this case, the force is no longer perpendicular to the door, so we must use the formula for the general case:

where

is the angle between the direction of the force and the face of the door

Substituting numbers into the formula, we find

it would be kevlar ^^

the area between the graph and the t axis