# Machine part ABC is supported by a frictionless hinge

In summary, the machine part ABC is supported by a frictionless hinge at B and a 10degree wedge at C. There is also a 120 lb force pushing to the right of point A. Knowing that the coefficient of static friction is 0.20 at both surfaces of the wedge, determine (a) the force P required to move the wedge to the left, (b) the components of the corresponding reaction at B.
The machine part ABC is supported by a frictionless hinge at B and a 10degree wedge at C. There is also a 120 lb force pushing to the right of point A. Knowing that the coefficient of static friction is 0.20 at both surfaces of the wedge, determine (a) the force P required to move the wedge to the left, (b) the components of the corresponding reaction at B.

I found the moment about C to be Mc=(-Byx10)+(-120x8)=> By=-96N
But I'm not sure where to go from there : /

Welcome to PF!

I found the moment about C to be Mc=(-Byx10)+(-120x8)=> By=-96N
But I'm not sure where to go from there : /

You haven't used µ = 0.2 yet …

show us what equations you get, and where you're stuck, and then we'll know how to help!

thats where I got stuck actually : / I know that to find the friction you would have to have a normal force to multiply M=0.2 by, I'm just not sure how to find the normal force : /

… I'm just not sure how to find the normal force : /

Acceleration normal to the surface is usually zero, so you usually find the normal force by taking components normal to the surface, and equating to zero.

So would the Moment about B or Mb = (-120x8) + (Nx10) work to find the normal force?

So would the Moment about B or Mb = (-120x8) + (Nx10) work to find the normal force?

(just got up :zzz: …)

Sorry, I'm confused because I don't really understand what the thing looks like,

(what shape is ABC? where is the wedge? is it fixed? etc )

but I don't see 10º or µ anywhere in that, so I'll assume it's wrong.

link13, that's hilarious … however did you think we were going to get that from your description?!

ok, a horizontal force P is trying to push a wedge to the left (at C), the top of the wedge slopes down to the left at 10º, and is held in position by pressure on its upper surface from an L-shaped object hinged at B (10 in. to the left of C) and pushed to the right by a horizontal force at A (8 in. above B).

Since the wedge is (obviously) not accelerating vertically, the net vertical force on it is zero, so the vertical reactions on both the upper and lower surfaces must be the same.

Find that reaction by considering the forces on ABC. Then find the friction forces. Then find P and the reaction at B.

alright i think i got got it now! Thanks! : )

## What is a frictionless hinge?

A frictionless hinge is a type of hinge that allows for smooth rotation and movement without any resistance or friction. It typically consists of two components that are connected by a pin or rod, allowing for free movement around the axis of the hinge.

## How does a frictionless hinge support a machine part?

A frictionless hinge supports a machine part by providing a pivot point for the part to rotate or move around without any resistance. This allows for smooth and efficient movement of the machine part.

## What are the advantages of using a frictionless hinge?

The main advantage of using a frictionless hinge is that it reduces friction and wear on the machine part, leading to increased efficiency and longevity. It also allows for smoother and more precise movement of the machine part.

## Can a frictionless hinge support heavy machine parts?

Yes, a frictionless hinge can support heavy machine parts as long as it is properly designed and installed. The weight and size of the machine part should be taken into consideration when choosing a frictionless hinge to ensure it can support the load.

## Are there any limitations to using a frictionless hinge?

One limitation of using a frictionless hinge is that it may not provide enough stability for certain machine parts. In these cases, additional support or a different type of hinge may be necessary. Additionally, frictionless hinges may be more expensive and require more maintenance compared to other types of hinges.

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