# Homework Help: Intrinsic critical speed of a steel circular shaft

1. Dec 24, 2013

### Mechatroni

1. The problem statement, all variables and given/known data
Determine the intrinsic first critical speed of a circular steel shaft supported by two bearings
E=207GPa

How can i determine it i'm very confused about this question , you can see the question at the attachment. Thanks for the help

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2. Dec 24, 2013

### SteamKing

Staff Emeritus
Specifically, what are you confused about? Do you understand how to calculate the critical speed of a shaft? Have you been exposed to the Rayleigh Method? Dunkerley's equation?

3. Dec 24, 2013

### Mechatroni

i'm not so good at this lecture. The part i'm confused is there is 3 different regions in the shaft so do i have to calculate for each of them and take the lowest one? i know the Rayleigh Method and the Dunkerley's Equation but i need to use m ( mass ) in those equations , the problem is only E is given to me. Where do i have to start to solve this

4. Dec 24, 2013

### SteamKing

Staff Emeritus
The OP says it is a steel shaft, so you can look up the density of steel and figure the mass of the shaft.

I think your first order of business is to analyze the shaft statically and determine its deflection between the bearings.