Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    2
    ReputationRep:
    The question is a mass of 5kg is suspended by two light inextensible strings, the angle between the strings and the vertical are 30 degrees and 60 degrees, find the tension in the strings.

    Right the thing Im struggling with is the diagram can anyone help with this?
    • Study Helper
    Online

    13
    Study Helper
    (Original post by SunDun111)
    The question is a mass of 5kg is suspended by two light inextensible strings, the angle between the strings and the vertical are 30 degrees and 60 degrees, find the tension in the strings.

    Right the thing Im struggling with is the diagram can anyone help with this?
    Name:  Untitled.jpg
Views: 95
Size:  20.1 KB
    Offline

    17
    ReputationRep:
    Something like the crude picture below:

    ====================
    ------\-------|---------------/----
    -------\------|------------/-------
    --------\-----|---------/----------
    ---------\30-|-60-/-------------
    ----------\---|---/----------------
    ---------||||||||||||| <- 5kg mass

    EDIT: I've been upstaged!
    • Study Helper
    Online

    13
    Study Helper
    (Original post by Farhan.Hanif93)
    EDIT: I've been upstaged!
    ninja'd :ninjagirl:
    Offline

    17
    ReputationRep:
    (Original post by ghostwalker)
    ninja'd :ninjagirl:
    This isn't the first time, and I'm convinced it won't be the last.
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by Farhan.Hanif93)
    This isn't the first time, and I'm convinced it won't be the last.
    Strill struggling, when I resolve vertically i get

    T1 (Tension 1) Sin30 + T2 (Tension 2) Sin 60 = 49

    Horizontaly
    T1cos30 = t2cos 60

    I cant rearrange it to get a equation to solve?
    Online

    22
    ReputationRep:
    (Original post by SunDun111)
    Strill struggling, when I resolve vertically i get

    T1 (Tension 1) Sin30 + T2 (Tension 2) Sin 60 = 49

    Horizontaly
    T1cos30 = t2cos 60

    I cant rearrange it to get a equation to solve?
    Are you sure you're using your sines and cosines right?
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by Zacken)
    Are you sure you're using your sines and cosines right?
    Ok maybe not

    But I got vertically
    T1 Cos 60 + T2 Cos 30 = 49

    Horizontally

    T1 Sin30 = T2 SIn 60

    I cant rearrange this for some reason?
    Online

    22
    ReputationRep:
    (Original post by SunDun111)
    Ok maybe not

    But I got vertically
    T1 Cos 60 + T2 Cos 30 = 49

    Horizontally

    T1 Sin30 = T2 SIn 60

    I cant rearrange this for some reason?
    It's just simultaneous equations. (assuming what you've written is correct) then plug the second equation into the first equation:

    T1 = (T2 sin 60)/(sin 30).

    Then plug this into the first equation to get an equation in terms of only T2.
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by Zacken)
    It's just simultaneous equations. (assuming what you've written is correct) then plug the second equation into the first equation:

    T1 = (T2 sin 60)/(sin 30).

    Then plug this into the first equation to get an equation in terms of only T2.
    Might have to give it to my teacher, to help me for some reason i can't get the right answer thanks for the help though/
    Online

    22
    ReputationRep:
    (Original post by SunDun111)
    Might have to give it to my teacher, to help me for some reason i can't get the right answer thanks for the help though/
    Why don't you post a picture of your working out?
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by Zacken)
    Why don't you post a picture of your working out?
    I worked it out, i just got confused between all the sin's and the cos's it is confusing when they is so many
    Online

    22
    ReputationRep:
    (Original post by SunDun111)
    I worked it out, i just got confused between all the sin's and the cos's it is confusing when they is so many
    Remember that you can always work out the trig values instead of dealing with the sines.

    So you could have written: \frac{1}{2}T_1 = \frac{\sqrt{3}}{2}T_2 \iff T_1 = \sqrt{3}T_2, etc... and same in the other equation.
    • Study Helper
    Online

    13
    Study Helper
    (Original post by SunDun111)
    I worked it out, i just got confused between all the sin's and the cos's it is confusing when they is so many
    You might like to try the triangle of force method with this question. Because the angle between the two tensions is 90 degrees, it succumbs to this method very easily.
 
 
 
Poll
Do you agree with the PM's proposal to cut tuition fees for some courses?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

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

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.