Stored energy calculation

[Bob B.]

I am currently working with the physics department in our high school and am attempting to create a lab that will calculate the efficincy of levers.  Naturally, I am thinking of bow limbs as the levers and the arrow the load.

I am having trouble finding a simple way to calculate stored energy so we can find Dynamic efficiency.

Any ideas out there?

Bob.

[tradlongbow]

Bob-

Contact Stu Miller, I bet he can help.
hkg3sg1@sbcglobal.net

Darren

[khardrunner]

If you are thinking specifically of a bow you can use the draw weight as elastic PE. Some conversion would be needed to get it into newtons from pounds, but a quick google search should rectify that.

[wingnut]

Bob,

Measure accurately the draw weight at each inch from brace to 28 inches.  Plot them on a graph and solve for the area under the graph.  There are some accurizing steps to smooth the graph lines but I think you get the idea.

That's will be the stored energy.

Mike

[cbCrow]

If you go to the A&H archery site to knowledge base they have a very good explanation of how to determine and I bet if you get in touch with them you might get some help with your project.

[moebow]

There is a book out there called "Archery the Technical Side."  It is a collection of articles all about the physics of archery.  C N Hickman, Paul Klopsteg and Forest Nagler are three of the authors.  These writers did this back in (I think) the 1930s but the science hasn't changed.

If you can find that book, it will answer many questions and show the math involved.

[Bob B.]

I appreciate the info fellas .. I have a good place to start.

   

Bob.