x Turn on thread page Beta
 You are Here: Home >< Maths

# Further maths forces help watch

1. Photo is below Please do then explain the process for me.

Thank you
2. I can't see a photo.
3. (Original post by old_engineer)
I can't see a photo.
It wont let me add a photo for some reason. Do you know any alternatives?
4. (Original post by amin11234)
It wont let me add a photo for some reason. Do you know any alternatives?
Courtesy of notnek:

Some users experience problems with attachments if they upload the image direct to TSR. If you are having problems then we recommend uploading the image to Imgur instead:

1) Go to http://imgur.com/ then click New Post at the top then browse to find your image.
2) Once the image is displayed, right-click on the image and choose "Copy Image Location". It is important you do this so you get the direct image link as opposed to the Imgur link.
3) To display the image in a TSR post you can paste this copied link into your post surrounded by [img][/img] tags
e.g. .
5. (Original post by old_engineer)
I can't see a photo.
Here it is sorry

https://imgur.com/gallery/Riwkm
6. (Original post by amin11234)
Here it is sorry

https://imgur.com/gallery/Riwkm
OK the suggested approach to part (i) of this question is:

1) Take moments about the bottom of the ladder, noting that the force exerted by the wall on the top of the ladder is purely horizontal. (It can’t have a vertical component because the wall is smooth).

2) Resolve forces horizontally. The ladder is in equilibrium, so the horizontal reaction at the wall must exactly balance the frictional force at the foot of the ladder.
7. (Original post by old_engineer)
OK the suggested approach to part (i) of this question is:

1) Take moments about the bottom of the ladder, noting that the force exerted by the wall on the top of the ladder is purely horizontal. (It can’t have a vertical component because the wall is smooth).

2) Resolve forces horizontally. The ladder is in equilibrium, so the horizontal reaction at the wall must exactly balance the frictional force at the foot of the ladder.
Ok thanks but how do you show that F=90(1+x)tan20?
8. (Original post by amin11234)
Ok thanks but how do you show that F=90(1+x)tan20?
If you take moments about the bottom of the ladder as suggested, everything should become clear. If it doesn't become clear, please post your working.
9. (Original post by amin11234)
Photo is below Please do then explain the process for me.

Thank you
https://imgur.com/gallery/Riwkm
10. This is the same image you posted three hours ago.
11. (Original post by old_engineer)
If you take moments about the bottom of the ladder as suggested, everything should become clear. If it doesn't become clear, please post your working.
https://imgur.com/gallery/MOKkw
12. The diagram is very difficult to read, but from what I can see, it may be useful for you to note that cos 70 is the same as sin 20. If you make that change you will have two sin 20 terms on one side of the equation and a cos 20 term on the other side, and you are aiming for an expression that involves tan 20.....
13. (Original post by old_engineer)
The diagram is very difficult to read, but from what I can see, it may be useful for you to note that cos 70 is the same as sin 20. If you make that change you will have two sin 20 terms on one side of the equation and a cos 20 term on the other side, and you are aiming for an expression that involves tan 20.....
ok, thank you for your help, finally got it.
14. (Original post by old_engineer)
This is the same image you posted three hours ago.

One more thing, for this question would there be two reaction forces: one at B and C or would there just be one on C?

thanks
15. (Original post by amin11234)

One more thing, for this question would there be two reaction forces: one at B and C or would there just be one on C?

thanks
You should reckon on there being reaction forces at both B and C. Bear in mind, though, that the reaction at C could be zero if the bridge was on the point of rotating anticlockwise about B. This would typically come about through the addition of an additional mass somewhere on the bridge.

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: February 5, 2018
Today on TSR

### Boyfriend slept with someone else

...we were on a break

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

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