## Angular velocity of a conical pendulum in rpm

1. The problem statement, all variables and given/known data
A conical pendulum is formed by attaching a 0.900 kg ball to a 1.00 m long string, then allowing the mass to move in a horizontal circle of radius 20.0 cm . What is the ball's angular velocity, in rpm?

2. Relevant equations
v=$$\sqrt{}L*g*sin(\vartheta)*tan(\vartheta)$$
w=v/r

3. The attempt at a solution
Since the radius is .2 m and the length of the string is 1m I used cos($$\vartheta)$$ and found $$\vartheta$$ to be 78.46 degrees. Then I used that equation for tangential velocity so I had v=$$\sqrt{}1*9.81*sin(78.46)*tan(78.46)$$ and got v=6.86 m/s so then I used w=v/r and got w=34.3 rad/sec which I then converted to rpm by multiplying 34.3 by 60 seconds times 1 rev/2$$\pi$$ and got 327.5 rpm and that is wrong. I don't know where I went wrong. I greatly appreciate any help.
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 Quote by kerbyjonsonjr 1. The problem statement, all variables and given/known data A conical pendulum is formed by attaching a 0.900 kg ball to a 1.00 m long string, then allowing the mass to move in a horizontal circle of radius 20.0 cm . What is the ball's angular velocity, in rpm? 2. Relevant equations v=$$\sqrt{}L*g*sin(\vartheta)*tan(\vartheta)$$ w=v/r 3. The attempt at a solution Since the radius is .2 m and the length of the string is 1m I used cos($$\vartheta)$$ and found $$\vartheta$$ to be 78.46 degrees. Then I used that equation for tangential velocity so I had v=$$\sqrt{}1*9.81*sin(78.46)*tan(78.46)$$ and got v=6.86 m/s so then I used w=v/r and got w=34.3 rad/sec which I then converted to rpm by multiplying 34.3 by 60 seconds times 1 rev/2$$\pi$$ and got 327.5 rpm and that is wrong. I don't know where I went wrong. I greatly appreciate any help.
I don't think you have the right angle. Double check how you got that.

 Tags angular velocity, pendulum, rpm