# ladder question (forces)

Watch
Announcements
This discussion is closed.
Thread starter 1 month ago
#1
Currently looking at ladder questions.

- Uniform beam, with mass m and length 2a, in equilibrium on rough ground and against a smooth wall.
- Horizontal force of magnitude kmg (k is a constant) is applied to the beam at A. This forces acts in a direction that is perpendicular to the wall and towards the wall.

I can model the first bit, however I'm not sure if I am modelling the second part correctly as I am getting a negative number for k.

Here's my drawing. Can someone please tell me if I have the additional force (kmg) drawn in the correct direction, and if not, can someone explain why please?

Thanks!
Last edited by bexxr; 1 month ago
0
1 month ago
#2
Can you upload a pic of the original question and what you tried?
Last edited by mqb2766; 1 month ago
1
1 month ago
#3
Could you upload the first part of the question?
It could be that mu*R is in the opposing direction and kmg is much larger, so friction is acting in the same direction as N? It would be an unusual scenario.
Last edited by mqb2766; 1 month ago
0
Thread starter 1 month ago
#4
mqb2766
Here's the first part of the question and my workings:
Last edited by bexxr; 1 month ago
0
1 month ago
#5
As its in equilibrium in part a) and you apply a force of kmg towards the wall, the limiting equilibrium means the ladder is about to slip UP the wall. So friction must be acting in the opposite direction (away from the wall), as suggested in the previous post.
Last edited by mqb2766; 1 month ago
0
Thread starter 1 month ago
#6
(Original post by mqb2766)
As its in equilibrium in part a) and you apply a force of kmg towards the wall, the limiting equilibrium means the ladder is about to slip UP the wall. So friction is acting in the opposite direction (away from the wall), as suggested in the previous post.
Oh, of course! I can't believe I didn't realise this (I feel a bit stupid now, haha!). Thank you so much for your help.
0
Thread starter 1 month ago
#7
mqb2766
Here's my revised workings. Would this be correct?
Last edited by bexxr; 1 month ago
0
1 month ago
#8
Looks good.
1
X
new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

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

### Poll

Join the discussion

#### What is your favourite revision method?

Taking notes manually (53)
21.72%
Note taking apps (6)
2.46%
Flashcards (47)
19.26%
Revision guides (15)
6.15%
Past papers (115)
47.13%
Something else (let us know in the thread) (8)
3.28%