How much damage would something that weighs three pounds do if it was traveling 250 feet per second?

Question

Obviously it would depend on how hard the three pound object was, what it hit and how far away it was when it hit it. So here it is, the object has a a hard plastic tip and has a base diameter of 40mm. The target is an unarmored person who get hit in the chest. At a range of 15 meters. For those who might know what I mean, I am wondering what a M203 round would do to someone if it hit them before it armed.

Answer 1

I'll assume air drag is insignificant at 15 m range.

Also assume V = vx = 76 mps (~ 250 fps) and mass m ~ 1.4 kg (3 lbs)

Then, KE = 1/2 mV^2 = (1/2)*1.4*(76)^2 = 4043.2 kg(m/sec)^2 (aka Joule)

By comparison, assume a car M = 1000 kg (2200 lbs) traveling v = 27 mps (60 mph) and we have KE = (1/2)*1000*(27)^2 = 364500 Joule or at v = 13.5 mps KE = 91125

It's clear the three pound shot at 250 fps would do far less damage than a car running into that person at 30 mph.  Working backwards from KE = 1/2 mV^2, we have V = sqrt(2KE/m) = sqrt(2*4043/1000) = 2.843589281 mps (6.353 mph) is the speed the 1 K kg car would travel to yield the same kinetic energy on the person.  So, as someone suggested, probably some bruises, but not much more.

Answer 2

It would do a lot of damage.

Answer 3

The answer is it will hit with 750 ft/lbs of force. It's going to crack ribs.

Answer 4

I don't think it would feel good, but i don't think it would kill them. might break a few bones.

Answer 5

Don't do it.  It will injure him.

Think of it in terms of kinetic energy.  K = 1/2 * m * v^2

If you plug the numbers in and convert to foot-pounds, it's 3000 ft*lb.

That's more energy than a bullet fired from a .50 caliber handgun.  Handguns kill.  There are revolvers that shoot bullets with only 181 ft*lbs of energy, and even those kill.  

This might not kill him because you said it's 4cm wide (though it doesn't sound like you were referring to the tip).  However, this will only divide the pressure by like 5.  While the energy is like 15 times more than a weak gun.  So this might overcompensate enough for it to succeed in killing him.

So not only will it injure him, don't be surprised if it KILLS him!

edit: i see someone mentioned a car going 30mph.  But remember, a car is much wider than a bullet, and therefore has much less pressure.  Pressure = force / area.  This is why bullets pierce you and cars don't.

Answer 6

the target would be dead or in bad shape with broken ribs. That's 170 mph. That's like swinging a hammer at someone's chest, and swinging it as hard as you could.

Someone calculated the equivalent kinetic energy to that of a car moving at 30 mph. But that's not a fair comparison, unless all the force of the car collision were concentrated in the same area.

Answer 7

You want to know the kinetic energy of the round

KE = (1/2) mv^2

Answer 8

That is roughly 170 mph (a level 5 hurricane starts at 156 mph) so I would have to think that your target would be dead when you finish your experiment, especially since your talking about a blow to the chest.

Answer 9

probably a lot of bad...I wouldn't suggest doing this to someone unless you're prepared to spend a significant period of time behind bars