Calculating Amplitude of a Simple Pendulum

[Mattmiles]

Homework Statement

A simple pendulum consists of a spherical bob of mass 0.052 kg and diameter 1.1 cm attached to a thread of length 920 mm.

b) The bob is released at rest with the thread taut at an angle of 5 degrees to the vertical. Calculate:
i) the amplitude of the oscillation

Homework Equations

The Attempt at a Solution

Am I right in saying it is tan(5) * 920 = 80mm round to 2 sig fig?

 

[HallsofIvy]

First we would need more information. I assume the string is attached at the top of the ball. Is that correct? So the total length of the pendulum is 93.1 cm? Where, on the pendulum are you measing to? The top, center, or bottom of the ball? And, what exactly do you mean by "amplitude"- the height the pendulum rises, the horizontal distance it covers, or the length of the arc? The last is the one I would assume but that is just the length of the pendulum times the angle in radians. And none is length times sin(5 degrees). That is the distance from the pivot point down to the height of the top of the pendulum at its highest point. The height it rises, the first of the three choices I mention, would be the length of the pendulum minus that.