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[Phys-l] A different normal force. Was: Re: The Normal Force



I've been working on a normal force problem that evidently is beyond my skill at 70. One method appears will work, but is too harry. the other, I suppose, I shouldn't give up so quickly, but I'm lazy, hoping one of you will solve it for me.

A wedge sits on a frictionless surface and a particle sits on the slopping surface of the wedge, w/ mass m (wedge is mass M). Find the reaction force as a function of the masses and the angle of the wedge. I tried the PE - KE (looks as it'll work, but just got too harry (70 repeating). So I switched to trying to fine the general cords. for the L. And got stuck. Anyone help?

bc


p.s. This has a practical app. if one desimplifies it. The particle is a cylinder that rolls down a curve. The "wedge" is attached to the pendulum of a clock. For my purpose, all I need is to use the reaction force as a torque and how does it (the torque) varies w/ an initial speed of the wedge (pendulum). The pendulum's amplitude is limited to about 30 milliradian, but the wedge is rather near the suspension.

Those of you, horologically inclined, will recognize this as the Synchronome escapement. The gravity escapement is "activated" every 30' very near BDC (The Airy criterion)

John Denker wrote:

On 05/24/2007 10:45 AM, Jeffrey Schnick wrote:


I'm just looking for a slightly more complete explanation, at
the same level--one that might also account for why stepping onto the
surface of a pond is so much different when the water is in its liquid
state than it is when the water is in its solid state.



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