Oscillations of a Pendulum: How Many Complete by Noon and What is the Amplitude?

AI Thread Summary
The discussion revolves around calculating the number of oscillations completed by a brass pendulum with a 15m wire by noon, starting from a 1.5m displacement at 8:00 a.m. The damping constant is noted as 0.010 kg/s, which affects the pendulum's motion. The user initially misapplied the formula for angular frequency, leading to an incorrect calculation of oscillations. Correcting this involves using the formula ω = √(g/L) while considering the damping effect. The amplitude question remains unclear, with suggestions that it may relate to the initial displacement rather than the wire length.
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Homework Statement



In a science museum, a brass pendulum bob swings at the end of a 15m long wire. The pendulum is started at exactly 8:00 a.m. every morning by pulling it 1.5m to the side and releasing it. Because of its compact shape and smooth surface, the pendulum's damping constant is only .010 kg/s.

At exactly 12:00 noon, how many oscillations will the pendulum have completed?

And what is its amplitude?

Homework Equations



w=2\pif
w=\sqrt{}k/m
T=1/f

The Attempt at a Solution



I used w=\sqrt{}k/m so I had w=\sqrt{}.01/110= .009 then I plugged that into w=2pif so .009=2pif f=.0015 and found the period by doing 1/.0015 and got 659 seconds. Then I converted the 4 hours minutes and got 14,400 and then I divided 14,400/659 and got 21.85.

For the amplitude I am not sure exactly how I would get that but would it just be the length of the wire or how high it goes or something else? Any help would be great. Thanks!
 
Physics news on Phys.org
Greetings! It looks like you confused k for b. Remember, in a simple pendulum,

\omega = \sqrt{\frac{g}{L}},

although you will still have to factor in the damping constant.
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

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