off topic physics question

[Camper]

Okay,

You have a 150gr bullet fired out of a gun let say going 2800fps
the gun is level with the ground about 5 feet high There is no wind.

your second bullet is dropped off the same height as the barrel "not fired out of a gun just dropped at the exact same time the other bullet is fired

Which one hits the ground first

[shafferm]

They hit at the same time, assuming that you drop the second one at the same instant that the first is exiting the barrel.

-M

[ComfyBear]

They hit at the same time, assuming that you drop the second one at the same instant that the first is exiting the barrel.

-M

That's not necessarily, correct. There's four possibly solutions.

A: The One dropped by hand.
B: The One fired out of the gun
C: Both hit the ground simulataneous
D: None of them hit the ground.

Although the rate of gravity acts the same on both bullets, at the rate of 9.8 m/s sq. You haven't taken into account other variables, which were not specified. As such there are four possible solutions.


Reasons:
A: The one fired out of the gun hit an object prior to hitting the ground
B: The one dropped by hand hit the table, and not the ground
C: This is assuming that both didn't meet any obstructions.
D: The one fired hit a deer, while the one dropped was caught before hitting ground.

Remember never ASSUME, since when you do, It can make an

ASS of U and ME



Here's one that you can ponder on. A glass that holds exactly 8 oz of liquid is filled with water right up to the rim and and also contains 2 ice cubes, each weighing exactly 1 oz. When the ice melts. how much of the water will overflow the glass. Now don't assume.

[shafferm]

CB,

I concur that you have covered the four possible scenarios, the one I went with was based on the feeling of this question being phrased in the context of a classical Newtonian physics sense. The point of which is to emphasize the fact that the velocity in the direction parallel to the ground is independent from that perpendicular to the ground. I am going to stick by my initial answer as being the most probable from the "spirit" within which it was phrased.

-M

[killshot]

I kinda agree with shafferm except when the bullet leaves the gun it is actually going to raise itself for the first 50 yards or so. Would that not make the hand dropped bullet hit the ground first? That is if the scenario from Shafferm is true.

[Houndsman]

Both bullets hit the ground at the same time only if this experiment could be performed in a vacum.

[ComfyBear]

CB,

I concur that you have covered the four possible scenarios, the one I went with was based on the feeling of this question being phrased in the context of a classical Newtonian physics sense. The point of which is to emphasize the fact that the velocity in the direction parallel to the ground is independent from that perpendicular to the ground. I am going to stick by my initial answer as being the most probable from the "spirit" within which it was phrased.

-M

Shafff, I was just playing, devil's advocate, and being a bit fastidious. It's my analytical nature to use the facts given to examine all possibilities.

do you have an answer to my glass of water question.

[FredBear]

do you have an answer to my glass of water question.

I say nothing would spill out of the glass. I believe the water would "crown" in the middle.

[shafferm]

ComfyBear,

First I will need a bit more info from you, first what are the starting temps of your ice,water, container, and surrounding atmosphere. What are the dimensions of your holding vessel, as this will greatly change the amount of expansion that will remain due to surface tension or crowning as FredBear pointed out. It will also relate to your evaporation rate. What are you using for evaporation rate of the water? What are you using as your sublimation rate of your ice? What is the composition of your water and ice, are you using dihydrogen monoxide(standard water), or deuterium oxide(heavy water) or a combination of the two? Your use of oz also seems ambiguous as it switches from measuring a volume in ounces to measuring a weight oz, you will need to be a bit more specific on these as well. What is your barometric pressure? Also, are there any other constraints on the system that I have not addressed or you have not yet mentioned?

Looking forward to more info,

-M


Here is a link that gives a bit more info on heavy water, you get ice cubes that will sink instead of float.

http://www.popsci.com/node/9240

[wabi]

The water shouldn't overflow, it's still only 8 fl oz. The ice is not in fluid form and is therefore floating above the surface level of the water, but when it returns to fluid form (melts) the volume of the contents of the glass will remain the same.
Unless some variable comes into play. (such as a thirsty observer)

[pdislow]

water expands when it freezes to make the ice cubes, so when the ice melts it actually shrinks back to water so therefore the glass will not run over unless the water in the glass is heated and expands which is not likely because as the ice melts the water temp should go down in the glass further decreasing the likelyhood of an overflow. my $.02

[mikej]

i'm going to stay away from these physics posts. way to advanced for me

[ComfyBear]

All good answers, it was a trick question. No water should overflow, unless spilt.

Reasoning;
No matter what the ice weighs, since ice is water in a solid state, it displaces the same volume. Furthermore, a 8oz glass that is filled to the rim, can only contain a maximum volume of 8oz. Whether that volume is in liquid or solid form is irrevelent.

When the ice changes state from a solid back to a liquid, there is no increase in volume. So none will overflow.

Since the question was, how much will overflow, it's irrevelent whether the volume changes by any method. (drank, evaporation or other)

[bomtek44]

killshot,

If the bore is dead level, the bullet of any gun, even a Super Humdinger Magnum Lightnin' Strike, will NOT rise above the line of the bore. Nothing overcomes gravity. This old tale is the result of the difference in line of bore and line of sight. If a gun is sighted for 50 yards, The bullet has to rise to intersect the line of sight. The higher the sight is above the bore, the "more" the bullet seems to rise.

They should hit the ground at the same time, but they will be "purty far" apart when they hit.

That's my story and I'm sticking to it,

[ComfyBear]

You tell'em bomtek44, that's good logic. It shows you've got your "thinking cap" on.