- #1

David Swift

- 3

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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.)

## 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?