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tomasblender

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## Homework Statement

In the arrangement shown in the figure, a mass can be hung from a string (with a linear mass density of μ=0.00182 kg/m) that passes over a light pulley. The string is connected to a vibrator (of constant frequency f), and the length of the string between point P and the pulley is L=1.95 m. When the mass m is either 16.5 kg or 22.5 kg, standing waves are observed; however no standing waves are observed with any mass between these values.

http://capa.physics.mcmaster.ca/figures/sb/Graph18/sb-pic1825.png

What is the frequency of the vibrator? (Hint: The greater the tension in the string the smaller the number of nodes in the standing wave.)

**What is the largest mass for which standing waves could be observed?**

f(m) = mf1

f = (T/u)^.5/2L

(16.5*9.8/0.00182)^.5/(2*1.95) = 79.249 Hz = (m + 1)f

(22.5*9.8/0.00182)^.5/(2*1.95) = 89.249 Hz = (m) f

Therefore

79.249 - 89.249 = mf + f - mf

10.000 Hz

Which is the incorrect answer.

## Homework Equations

f(m) = mf1

f = (T/u)^.5/2L

## The Attempt at a Solution

(16.5*9.8/0.00182)^.5/(2*1.95) = 79.249 Hz = (m + 1)f

(22.5*9.8/0.00182)^.5/(2*1.95) = 89.249 Hz = (m) f

Therefore

79.249 - 89.249 = mf + f - mf

10.000 Hz

Which is the incorrect answer.

**would be**

(mg/u)^.5/2L = Answer for part A

("a"^2)*(2L^2)*u/g = m

I cannot test if this is the answer without having the answer for the first section. Anyways I am dry out of ideas for part A, any help?(mg/u)^.5/2L = Answer for part A

("a"^2)*(2L^2)*u/g = m

I cannot test if this is the answer without having the answer for the first section. Anyways I am dry out of ideas for part A, any help?

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