You are Here: Home >< Maths

# m2 reaction force at hinge Watch

1. I'm some moment questions they ask you to find the reaction force at a hinge, what does that mean?
As far as I know, a reaction force is an object applying an equal and opposite force on another object.
2. When the object (let's say a rod) is attached to the hinge, there is a *up* force which can be found by resolving against all the vertical components; against the weight of the rod, for example. There is also an *across* force which can be found by resolving against all the horizontal components in a similar way.

By using Pythagoras Theorem, we can find the *magnitude* of the force at the hinge by creating a right angled triangle (with the sides equivalent to the *up* and *across* forces), and we can also find the angle that this magnitude makes with the vertical.
3. (Original post by Giant)
When the object (let's say a rod) is attached to the hinge, there is a *up* force which can be found by resolving against all the vertical components; against the weight of the rod, for example. There is also an *across* force which can be found by resolving against all the horizontal components in a similar way.

By using Pythagoras Theorem, we can find the *magnitude* of the force at the hinge by creating a right angled triangle (with the sides equivalent to the *up* and *across* forces), and we can also find the angle that this magnitude makes with the vertical.
Thanks!
4. (Original post by Giant)
When the object (let's say a rod) is attached to the hinge, there is a *up* force which can be found by resolving against all the vertical components; against the weight of the rod, for example. There is also an *across* force which can be found by resolving against all the horizontal components in a similar way.

By using Pythagoras Theorem, we can find the *magnitude* of the force at the hinge by creating a right angled triangle (with the sides equivalent to the *up* and *across* forces), and we can also find the angle that this magnitude makes with the vertical.
Actually one last question, if the thing hinged at an angle, do you resolve the forces perpendicular and parallel to the plane or to horizontal and vertical?
5. (Original post by eggfriedrice)
Actually one last question, if the thing hinged at an angle, do you resolve the forces perpendicular and parallel to the plane or to horizontal and vertical?
Since we need the magnitude in relation to the plane, I tend to do it perpendicular and parallel to the plane.
6. (Original post by Giant)
Since we need the magnitude in relation to the plane, I tend to do it perpendicular and parallel to the plane.
That's what I thought, but looking at my teachers hand written answer he did it the other way. :/

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: April 9, 2013
Today on TSR

### Falling in love with him

But we haven't even met!

### Top study tips for over the Christmas holidays

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.