doubling shotgun = 4x recoil energy?

[BigJimP]

.45 Colt - you are correct / thanks for catching my error.

My original calculation did not double the weight of the wad. When I did the math again (this time including the weight of the 2nd wad as well ) / the recoil from both barrels going off at the same time is 4.000 times the original recoil. 81.62 Ft Lbs vs the original 20.40 Ft Lbs.

 

[zippy13]

I'm old enough to have taken my university engineering pre hand-held calculator. With a slide rule, one could lose track of the decimal point's position -- it was common for the numbers to be correct, but off by several factors of 10. Consequently, designs based on those calcs could be off by factors of ten, also.

One of the most valuable things I learned was from an old Heidelberg Don... A student's concrete column had an unbelievable amount of reinforcing steel, and the student said his numbers supported the design. The professor replied, "I don't care how accurate your numbers are, is your solution reasonable?"

You need to ask yourself, does quadrupling the recoil when a shotgun doubles seem reasonable? Initially, it didn't to me, yet I've run the numbers several times using different approaches. Like BigJimP's numbers, mine support the 4 X times increase. Numbers aside, it's DaveBeal's simple explanation that seems to clarify the physics.

 

[BigJimP]

I agree Zippy .... Slide Rules and Fortran IV punch cards ..... now those were the days ....before hand held calculators were even invented...
I'm old enough to have done it the old way too....and an Excel Spreadsheet is sure a big time upgrade over those days.....

but since I blew the calculation .... your point is well taken as a reminder that using it still depends on the ability to reason your way thru the problem, checking the forumlas, and checking and verifying the results ( which I didn't do )... ( and making sure the results I saw were reasonable ) which I didn't do obviously...

Doing it quick / and blindly regurgitating the numbers - is no shortcut for doing it correctly. But this was an interesting thread - because initially, I didn't think it was 4 Times ....and it led me astray. I may have napped during some of those physics classes in the early 70's .....

 

[DaveBeal]

You need to ask yourself, does quadrupling the recoil when a shotgun doubles seem reasonable?

Felt recoil is a much more complicated topic than total recoil, because it depends on how suddenly the recoil occurs, and because it involves human perception. I don't know whether felt recoil is more closely related to recoil momentum or recoil energy, but I agree that the quadrupling of recoil energy, while true, is counterintuitive.

Numbers aside, it's DaveBeal's simple explanation that seems to clarify the physics.

Glad you like it!