How hard can you push something given grip strength?

[dlpoehlman]

Hello,

I was hoping you could solve an argument. We are wondering how hard you can push something. Let's say I have a piece of wood clamped down on a table and I want to push the piece of wood left or right. If the clamp is pushing down on the piece of wood at 100 pounds, I would need 100 pounds given the static coefficient of friction of skin is 1.

 

[NascentOxygen]

Hi dhpoehlman. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

Calculations based on coefficient of friction relate to parallel surfaces sliding. Imagine pulling a vertical pipe out of the ground vertically.

I can't quite picture the image you describe. You'll need to be attempting to move an object having parallel sides in a direction along its principal axis.

 

[dlpoehlman]

I think the same principles work with pulling a verticle pipe out of the ground vertically if that helps you visualize.

 

[jbriggs444]

If the clamp is pushing down on the object with 100 pounds of force, that does not tell you anything directly about how well that will hold it against left or right movement. For that you would want to know the coefficient of friction of clamp on object. But let us assume instead that the clamp is pushing down just hard enough that the object will resist 100 pounds of left or rightward force.

Now, how do you measure grip strength? Do you, for instance, imagine your hands as a rubber band encircling the object with a tangential tension of x pounds? That would result in a radial pressure of pi x pounds if you added up the incremental force all the way around the circumference of a circular object. Or do you imagine your hands as a clamp exerting equal and opposite pressure on two sides of the object. That would result in pressure of 2 x pounds if you add the force on both faces.