Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: [Phys-l] bound vectors ... or not



On 09/07/2010 05:19 PM, Jeffrey Schnick wrote:

Another way to see that the torque exerted on the disk by the pin in the
first configuration is greater than the torque exerted on the disk by
the pin in the second configuration is ...

Another way is by the principle of virtual work.

The work done by the linear motor is F • dx.
The work done by the disk is torque • dθ.

As θ goes from 0.00001 to 45 degrees, the work
done by the linear motor is finite.

As θ goes from 45 to 89.99999 degrees, the work
is more than a million times larger.

Same Δθ with different work means different torque.

============

A pin in a slot at point X is not the same as a
plain old force attached to point X. There are
leverage issues.

As for the problem of converting uniform rotary
motion to uniform linear motion, a _screw_ is a
famously good solution.