Kenetic Energy Formula

[2 Barrels]

Hello,Could someone give me the formula to figure kenetic energy in foot pounds?Thanks,Jim

[Mike Burch]

speed x speed x mass / 450240.

[Winterhawk1960]

Formula

For an object that is moving the kinetic energy equals one half times the mass of the object times the square of the speed of the object. In symbols:

EK = (1/2)mv2


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Example Calculation

How much kinetic energy does an object have if its mass is 5.0 kg and it is moving at a speed of 4.0 m/s?

EK = (1/2)mv2 Formula for kinetic energy.
EK = (1/2)(5.0 kg)(4.0 m/s)2 Plug in values for mass and speed.
EK = 40 J Kinetic Energy equals 40 J.

Winterhawk1960

[gjarcher]

KE = 1/2mv^2

 http://utopiaprogramming.com/ke/KineticEnergy.html#

However, I place much more importance on Momentum as an indicator of penetration potential.

[Winterhawk1960]

But.........I think the "momentum" formula is more conducive to an arrows ability to "penetrate".

Momentum = mass X velocity

Winterhawk1960

[trcytylr]

Ya'll givin' me a headache   :confused:    

[2 Barrels]

Thanks guy i used to know that.Now i know alot of other stuff that i'll eventually forget as well.Thanks,Jim

[Bob B.]

Gentleman,

The formula for momentum is a bit tricky, but is truely a much better fromula to use when looking for the "impulse" a moving object has.  In other words, KE (kenetic energy) loses it's energy rapidly and thus when applied to an arrow is of little use to determine potential for lethality.  Impulse force, (momentum) is a far better tool to compare how much opposing force is required to stop an oject in motion as Momentum expressed in slugs loses its energy quite slowly as compared to Kenetic Energy.

So, a basic formula is mass times velocity divided by the gravitaional constant of the Earth.

For arrows, use, arrow grains times FPS divided by 225218.  This will give you a number in slugs.  (This formula does not take into account mecanical advantage for what type of broadhead used.)

So a 600 grain arrow traveling in a staright line at 162 FPS divided by 225218 equals .43 slugs.  

.43 slugs is a big number! A number around .32 -.36 is fine for deer. A number of about .38 to .40 is good elk medicine.  .43 can handle some pretty large animals.  This formula will favor heavy over fast in terms of greatest potential for leathality.

Slugs over joules when determining a good hunting set up.

Bob.

[wapiti792]

Man you guys are wayyyy smart. F=M(A)...that's all I remember from my college physics coarse, but that's force and not KE. I hunted too much at the local WMA to get an A    Thank goodness I only needed on semester