Year 12s: what will be the first way you research your future options? >>

M2 Mechanics question

username1432214

What does freely hinged mean? Does it mean it always have 2 reactions x and y?

Reply 1

Ayman!

Original post by Bealzibub

What does freely hinged mean? Does it mean it always have 2 reactions x and y?

"Freely hinged" means that the rigid body is being held in place from a certain point. Imagine the following example: a sheet of paper (lamina) is held in place from its corner by a pin. Here, the pin is acting as the hinge and if the hinge were not exerting a reaction force on the lamina, the lamina would just fall down due to its weight.

A hinge exerts one reaction force, but for the sake of simplicity we break this reaction force into its constituent horizontal and vertical components X and Y.

You will often find a later part of a moments question to "find the magnitude and direction of the reaction force". This is basically using Pythagoras' theorem on X and Y and finding the angle at which the reaction force acts and its magnitude.