Re: Problem with a problem

[Richard Tarara <rtarara@SAINTMARYS.EDU>]

----- Original Message -----
From: "Harry L. Hightower" <htower@BROOKSTONE.GA.NET>

>         How do you go about solving the following problem?
>         A thin rigid rod is rotating with a constant angular
> acceleration about an axis that passes perpendicularly
> through one of its ends. At one instant, the total
> acceleration vector (centripetal plus tangential) at the
> other end of the rod makes a 60.0 degree angle with
> respect to the rod and has a magnitude of 15.0 m/s/s.
> The rod has an angular speed of 2.00 rad/s at this
> instant. What is the rod's length?
>         I am probably making this harder than what it really is.
>
>                                            Thanks
>                                                    Harry

Find the radial component of the acceleration.  This is then the centripetal
acceleration.  You know the angular speed (at this moment in time) so use
that to find R.  The fact that there is a net torque that will subsequently
change the angular speed is the 'red herring' here.  It doesn't enter into
the calculation.

Rick

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Richard W. Tarara
Department of Chemistry & Physics
Notre Dame, IN 46556
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rtarara@saintmarys.edu

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