physics
posted by jamieson .
a conical pendulum is formed by attaching a 500g ball to a 1m long string then allowing the mass to move in a horizontal circle of radius 20 cm.
A) what is the tension of the string?
b) what is the balls angular speed in rpm?

A) Perform a vector addition of the weight and the mass x (centripetal acceleration). The two forces act in perpendicular directions, and the resultant is the tension, T.
B) T sin A = M V^2/R, from a horizontal force balance. Solve for V.
A is the angle of the string from vertical. Solve for V
Use V and R to get the rpm.
2 pi R/T = V
where T is the time required for the ball to go around once, in seconds.
RPM = 60/T 
ds