- #1
David Swift
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1. Relevant information
A bob of mass 0.5kg is attached to one end of a light inextensible string of length 0.500 m, whose other end is attached to a fixed pivot. The bob performs uniform circular motion in a horizontal plane, with the string making an angle of 30.0° with the vertical.
2. Question
What is the angular speed of this circular motion?
Hint: you can begin by using Newton's second law in the vertical direction to find the tension in the string.)
Tension in string
F Cos 30 = 0.5 x 9.81
F = (0.5 x 9.81) / Cos 30
F = 5.66N
Radius of circle must be 0.5x Sin 30 = 0.25m
F = mass x radius x angular speed^2
Angular speed = Sqrt ( 5.66 / (0.5 x 0.25))
Angular speed = 6.72 rad s^-1
Have I done this right?
A bob of mass 0.5kg is attached to one end of a light inextensible string of length 0.500 m, whose other end is attached to a fixed pivot. The bob performs uniform circular motion in a horizontal plane, with the string making an angle of 30.0° with the vertical.
2. Question
What is the angular speed of this circular motion?
Hint: you can begin by using Newton's second law in the vertical direction to find the tension in the string.)
The Attempt at a Solution
Tension in string
F Cos 30 = 0.5 x 9.81
F = (0.5 x 9.81) / Cos 30
F = 5.66N
Radius of circle must be 0.5x Sin 30 = 0.25m
F = mass x radius x angular speed^2
Angular speed = Sqrt ( 5.66 / (0.5 x 0.25))
Angular speed = 6.72 rad s^-1
Have I done this right?