# Urgent maths help!!!

anyone know where this question is from???

A ladder AB has mass M and length 6a.

The end A of the ladder is on rough horizontal ground.

The ladder rests against a fixed smooth horizontal rail at the point C.

The point C is at a vertical height 4a above the ground.

The vertical plane containing AB is perpendicular to the rail.

The ladder is inclined to the horizontal at an angle a, where sin a= 4/5,, as shown in Figure 1.

The coefficient of friction between the ladder and the ground is u.

The ladder rests in limiting equilibrium.

The ladder is modelled as a uniform rod.

Using the model,

(a) show that the magnitude of the force exerted on the ladder by the rail at C is 9Mg/25

(b) Hence, or otherwise, find the value of mu.
Not certain, but it looks very similar to some of the questions here: https://mathsmartinthomas.files.wordpress.com/2014/12/m2-statics-pastq.pdf
Ladder questions like this are ubiquitous. What makes this one a bit unusual is that the ladder rests against a rail rather than a wall. Why do you need to know where it's from?
Did you ever find out where this question is from I had in my recent paper and I just want to see the solutions as I keep getting 9Mg/20

But when I model the rod as non uniform I get 9Mg/25.

And now I'm a bit paranoid about what mu could be 🥲
Was there a diagram for this question

Well I worked it out I had a diagram in my question but it never stated 4a as a height
Original post by scoobiedoobiedoo

Well I worked it out I had a diagram in my question but it never stated 4a as a height

good
(edited 3 years ago)
That's correct. 18/49
Original post by scoobiedoobiedoo

Well I worked it out I had a diagram in my question but it never stated 4a as a height

hello, thanks so much for working through this publicly i was so stuck! would you be able to explain to me your horizontal forces because i couldn’t get the Rcsinx to be horizontal, only diagonal :/
Original post by FaccoyKazz
hello, thanks so much for working through this publicly i was so stuck! would you be able to explain to me your horizontal forces because i couldn’t get the Rcsinx to be horizontal, only diagonal :/

Oh my I did this question such a long time ago aha but if you are really stuck on forces and static rigid bodies I suggest for you to look at the website maths genie a level revision.

He does revision videos for all topics as well as questions for you to work on with solutions.

Maths takes a lot of practise and time aha
Original post by scoobiedoobiedoo
Oh my I did this question such a long time ago aha but if you are really stuck on forces and static rigid bodies I suggest for you to look at the website maths genie a level revision.

He does revision videos for all topics as well as questions for you to work on with solutions.

Maths takes a lot of practise and time aha

no worries i understand it was a long time ago!😂thanks so much for the suggestion i definitely will have a look!
drfrost has very good questions
Original post by scoobiedoobiedoo
Did you ever find out where this question is from I had in my recent paper and I just want to see the solutions as I keep getting 9Mg/20
But when I model the rod as non uniform I get 9Mg/25.
And now I'm a bit paranoid about what mu could be 🥲
Yes same I am so confused 😕
Original post by Grace xox
Yes same I am so confused 😕

I just googled part of the question and it came up with a YouTube walkthrough - apparently it's Edexcel A-Level Mathematics - October 2020 - Mechanics - Question 4

Edexcel A-Level Mathematics - October 2020 - Mechanics - Question 4 - Exam Paper Walkthrough - YouTube
Original post by davros
I just googled part of the question and it came up with a YouTube walkthrough - apparently it's Edexcel A-Level Mathematics - October 2020 - Mechanics - Question 4
Edexcel A-Level Mathematics - October 2020 - Mechanics - Question 4 - Exam Paper Walkthrough - YouTube

oh ok thanks I'll take a look