# Lever equations

1. Apr 18, 2006

### tompotts

Hi everyone,

Im designing a new device for openeing bottle caps. But Im stuck,

basically I have a second class lever (pivot at one end, effort at the other and weight in the middle). The weight is 72.21N the overall length from the effort to the fulcrum is 64mm and the length from the weight to the fulcrum is 15mm.

I need to find out how I can convert the effort that needs to be exerted into units suitable for choosing materials (ie. ultimate tensile strength). How do I convert the (effort) force from Newtons to UTS or yeild strength. I have tried and tried to get my head around this one but i just cant figure it out.

I can imagine that this is really pretty simple, but I cant get my brain into gear. If anyone can help it would be greatly appreciated.

Thanks guys, have fun

Last edited: Apr 18, 2006
2. Apr 19, 2006

### Fermat

If you are looking for materials to use then you will have to consider the sheer force in the lever.
What's the maximum shear force (at the smallest cross section). Can you do a Shear Force diagram? Then you (may) have to take a factor of safety into account. Then browse for materials with an appropriate UTS/YS.
Once you know the maximum shear force, then go http://www.onlineconversion.com/" to convert fom N/mmÂ² to whatever. Goto "Pressure"

Last edited by a moderator: Apr 22, 2017