Question

I need HELP Pleassseeee!!!!

Answer 1

Firstly - they state the ring is 'smooth. This means the tension is the same in AR as in BR.

THe diagram shows all the forces acting on the apex r:



You can derive some other angles from the geometry: 3 angles = theta



So oyu can resolve the 2 tensions vertically and they must balance the weight
resolve them horizontally - they balance the pulling force


Sart there - see how you do...

Answer 2

I pretty much got that part, but how do you resolve the angles

Answer 3

In the answer they had
Tcosθ + Tsinθ = 15.5
–Tcosθ + Tsinθ = 8.5

Answer 4

How did they arrive at that?

Answer 5

do you know how to resolve a force into components?

Answer 6

Yes, but this one has been quiet tricky

Answer 7

so
what is the horizontal component of the tension in AR?

Answer 8

Tcosθ

Answer 9

and
what is the horizontal component of the tension in BR?

Answer 10

BR is where I found it tricky :(

Answer 11

you are used to having the angle to resolve in
but in this case you have a right angle triangle between BR, the vertical, and the horizontal
so the force is at 90-theta to the horizontal

can oyu work from that?

Answer 12

okay and cos(90-θ) is sinθ

Answer 13

I see it now :) thanks

Answer 14

The 2 equations come from resolving horiz and vertical

They are independent simultaneous equations so the answers drop out from them

Answer 15

Could you rephrase that?

Answer 16

You have correctly got the cos(90-theta) = sin(theta)
So the first equation you gave above is from resolving horizontal components

The second equation will come from a similar process in resolving vertical forces

The 2 equations are independent (since horiz and vert forces do not affect each other)
They are also simultaneous (since both are true from the same system)

So oyu can solve the two equations by whatever method you know for simultaneous equations.

That gives you the values for TsinTheta, and TcosTheta as given in the question

Find TanTheta from those, and hence theta

Answer 17

As a general point - if you resolve forces or vectors, then if 1 axis is Fcos Theta then the other is Fsin Theta

Answer 18

Thanks Thanks I got that :)

Answer 19

Well done. :-)