Circular Motion with Tension and Finding Angle

[Physkat]

Homework Statement

A 0.020-kg mass is attached to a 1.2-m string and moves in a horizontal circle with a constant speed. The tension in the string is measured at 0.200 N. What is the measure of angle θ?

Homework Equations

∑F=ma, a=v^2/r

The Attempt at a Solution

I broke down the forces at work, being T (tension) and W (weight). I made a free body diagram, then drew a graph. I came up with the x components as -Tsinθ=ma, and y components as Tcosθ-W=0. After plugging in for T and m*g (from W) in the y component equation, I came up with θ=11.2, but this is not correct.

 

[haruspex]

The question as posted does not indicate whether the angle is to be measured from vertical or from horizontal. I assume there is some diagram which makes it clear it is to the vertical.
I agree with your answer in degrees. Are you sure the question does not want the answer in radians?

 

[Physkat]

Haruspex,
Thank you for your response. Here is the image associated with the problem.

 

[haruspex]

Then I see only four possibilities:
- you were expected to use a slightly different value of g; the answer will be somewhat sensitive to this, .980 giving 11.5 degrees e.g.
- for the same reason, you should only specify two sig figs.
- the answer should be in radians
- the book is wrong (maybe in the question statement)

 

[Physkat]

Haruspex, thank you. I'll have to do some digging, but it gives the answer as 24.6 degrees. So I'll try to get to the bottom of it. Thanks again!