Question

Hey all! In the following problem I need to draw the free-body diagram of the cylinder an determine the magnitudes of AC and CD:

The hydraulic cylinder is subjected to three forces. An 8 kN force is exerted on the cylinder at B that is parallel to the cylinder and points from B toward C. The link AC exerts a force at C that is parallel to the line from A to C. The link CD exerts a force at C that is parallel to the line from C to D. I'll include the image in the comments.

Answer 1

Here is a rough sketch of the problem, with included dimensions.

Answer 2

I need the free body diagram. I can figure it out from there.

Answer 3

Attempt to draw it yourself first; and I'll correct it :)

Answer 4

Ok here is what I got, but it makes no sense to me. There must be normal forces somewhere but I'm not sure where to put them:

Answer 5

I think the three forces are themselves normal forces (or tension; whatever you are used to call them).

Answer 6

Wait wha........but i'm still missing forces in order to balance aren't I? as it is now point C should be moving upward. There must be some force keeping it down right?

Answer 7

Honestly, I don't know how this arrangement will work (or what purpose it is used for). As we are using rods (instead of strings), the tension will change its direction from compressional to extensional (or vice-versa) to keep the point C in equilibrium.

Answer 8

Consider posting the original question.

Answer 9

This question is coming out of my textbook so I'm not sure how to get it from the page to here.

Answer 10

If you have a camera, upload the image.

Answer 11

ok in proceso.

Answer 12

Ok I got it:

Answer 13

@Mashy

Answer 14

@Vincent-Lyon.Fr
@douglaswinslowcooper
@Garm

Answer 15

@UnkleRhaukus

Answer 16

Took some time, but I think I understand it now. (Note that the arrows indicate force vectors.)

Try to find how I chose between compressional and extensional tension?
Also, find where does Fex comes from?

Answer 17

^^ @alffer1

Answer 18

ok yeah I'm looking at it now. I understand where everything is coming from except the Fex. the problem doesn't say anything about an external force being applied...

Answer 19

It's not an external force; take a closer look at the diagram.

Answer 20

I used the term Fex in the same sense as "...Cats are liquid" :D

Answer 21

ok let me see if I understand the diagram: the forces in each of the rods causes a reaction force at the other points. The liquid in the cylinder is compressed causing a reaction force from the liquid?

Answer 22

There is also a string attached to the hydraulic cylinder.

The hydraulic part only involves the fact that we can convert a weaker force into a stronger one; simply by changing the area on which the force is applied.

Answer 23

OHHH so the tension in the string pulling backwards is what is causing Fex?
and it's equal and opposite to the 8000 N force?

Answer 24

For more on hydraulics; read - http://en.wikipedia.org/wiki/Hydraulic_drive_system.

"...OHHH so the tension in the string pulling backwards is what is causing Fex?..."
Yes

"...it's equal and opposite to the 8000 N force?..."
You can do the (vector) addition yourself as I am a very lazy guy :D

Answer 25

ok awesome this actually makes sense now. just needed to figure that out.

Answer 26

Could you take a look at one quick question?

Answer 27

Yea, ask away

Answer 28

http://openstudy.com/study#/updates/52db802ee4b003c643a003f5