- #1
deezy
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Homework Statement
A student ties a 400g rock to a 1.0m long string and swings it around her head in a horizontal circle. What angular speed does the string tilt down at a 10° angle?
m = 400g = .4kg
r = 1m
Homework Equations
[tex]F = \frac {mv^2}{r}[/tex]
[tex]\omega = \frac {|v|sin \theta}{|r|}[/tex]
[PLAIN]http://img31.imageshack.us/img31/7350/circ1.png
[PLAIN]http://img513.imageshack.us/img513/513/circ2.png
The Attempt at a Solution
First I solved for the tensions:
[tex]T_y = 9.8 * .4 = 3.92N[/tex]
[tex]tan 10 = \frac {3.92}{T_x}[/tex]
[tex]T_x = 22.23N[/tex]
Then for velocity:
[tex]22.23 = .4 * \frac {v^2}{1}[/tex]
[tex]v = 7.45 m/s[/tex]
Then for angular speed:
[tex]\omega = \frac {7.45 sin 10} {1}[/tex]
[tex]\omega = 1.29°/sec[/tex]
I wasn't sure if I set this up correctly or used the right formulas. I also wasn't sure if my answer was in the correct units. I also wanted to know if the picture for this motion is like the 1st picture or the 2nd picture? I used the first picture to solve this problem.
[tex][/tex]
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