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?

1 answer

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