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The most common use of hinges is to allow opening and closing between two objects. Torque represents the amount of force that is exerted by the swinging object, such as a house door or a cabinet door, during the movement process. Friction occurs between the different pieces of the hinge and is directly related to the weight of the swinging object, the length between the centre of gravity and the hinge and the degree to which the hinge can rotate.
Measure the distance, in inches, between one of the hinges and the centre of the door to obtain the centre of gravity distance.
Weigh the door, in pounds, on a scale or search for the weight in the instruction manual.
Multiply the centre of gravity distance by the door's weight to calculate the torque. The International System of Unit (SI) of torque is measured in newton meters (Nm). For example, if the distance between the hinge and centre of gravity is 24 inches and the weight of the door is 63.5 Kilogram, the torque would measure 3,360 Nm (24 x 140 = 3,360).
Calculate the angle of the door opening and closing. Measure the maximum angle in which the door can be opened by laying the protractor's flat side against the door and swinging open the door all the way. Most hinges can open a full 180 degrees unless the door is protected by a door stopper or another obstruction.
Multiply the angle by the torque to calculate the friction, in newtons (N). For example, if the door can only be opened 120 degrees and the torque is 3,360 Nm, the friction is 403,200 Newtons (120 x 3360 = 403,200).
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