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M1 question

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?
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?


Untitled.jpg
Something like the crude picture below:

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

EDIT: I've been upstaged!
(edited 7 years ago)
Original post by Farhan.Hanif93

EDIT: I've been upstaged!


ninja'd :ninjagirl:
Original post by ghostwalker
ninja'd :ninjagirl:

This isn't the first time, and I'm convinced it won't be the last.
Reply 5
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?
Reply 6
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?
Reply 7
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?
Reply 8
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.
Reply 9
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/
Reply 10
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?
Reply 11
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
Reply 12
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: 12T1=32T2    T1=3T2\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.
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.

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