There aren't any decent looking females in the physics classes. That's
why I played hooky in the Bio-chem. labs. Blonde, great curves,
friendly, Berkeley coeds....wow 8-)
S. Evan

ATP wrote:

JTMcC wrote:

"ATP" wrote in message
news
JTMcC wrote:

"jim rozen" wrote in message
...

In article , JTMcC says...


I would think the effect of gravity
and wind resistance would determine the maximun velocity of the
falling bullet

The phrase is 'terminal velocity' and I suspect that for
any modern round fired straight up, this is indeed the
determining factor, so I would put my guess in line with
yours. As you suggest, there are others here who truly
know the answer off the top of their heads.

Jim

I'm aware of terminal velocity, and have reached it a time or two. I
can reach it while falling from a height, regardless of my velocity
in reaching that height, therefor my difference of opinion with the
post about the bullet dropping at the same speed it initially rose.
I can jump (fall, be pushed out of) an airplane at a height of 1000
ft and I will achieve a certain speed before wind resistance
prevents any further increase. I can also be shot from a cannon
straight into the air, or simply step off a platform at 1000 feet
and still, my velocity toward the earth is limited by drag. If I
spend 7 hours climbing to the 1000 foot mark, or ascend in a matter
of seconds via F-16, my upward velocity matters not to the downward
velocity I attain. That is my take, but then I wasn't even paying
attention in H.S. physics.

JTMcC.


You are right that it does not matter how you get there, but the
initial velocity does matter in projectile motion problems. That is
the only energy the projectile has, and it will be converted into a
higher potential energy until it has zero kinetic energy at the very
top. Putting aside air resistance, initial velocity and elevation is
all we need to determine the maximum height the projectile will
reach. There are several ways the problem can be solved, but
comparing energy states is probably the most intuitive.

We don't care how high it goes, we only care about it's velocity
returning to earth, after coming to a theoretical stop after being
fired straight up. We are talking about bullets with no energy
remaining from the initial firing.


No kinetic energy remaining, they have potential energy due to their
increased height, relative to some lower height. The potential energy is
proportional to the height.


I can go out in my fromt yard

right now, and fire a .22 caliber, 55 grain projectile into the sky
at around 2800 fps (feet per second) or over 4000 fps. Using my
original criteria of the bullet flying straight up, until stopped by
the force of gravity, and returning to earth via the same
gravitational force, do you really believe the bullet fired from a
220 Swift or 22-250 will hit the ground at a greater speed than the
one fired from a .223? Again, I was more interested in the girl
sitting next to me in H.S. physics class than the math problems, but
I'm still pretty sure I'm right.

JTMcC.


If you are considering air resistance, any bullet fired up is going to have
sufficient kinetic energy and attain a sufficient height to return at
terminal velocity. We have to either simplify the problem by neglecting air
resistance or consider all factors, which would get pretty complicated. In
any case, energy is conserved and theoretically can all be accounted for, in
terms of heat, work done on the greater environment, etc.. As far as physics
class, the important thing in any lab class is to snag a decent looking girl
as a lab partner early on...