Will a fired bullet hit the ground at the same time as a dropped bullet?

A little fun for the crew to consider. A popular T.V program ran an episode a number of years back that answers these questions. I'll post their results after a day or so to give those who wish to play along time to guess.

Two questions, How far do you think a .45 ACP bullet will travel if the muzzle is perfectly level at firing at about waist level?
Will a perfectly level fired bullet and a dropped bullet hit the ground at the same time if they're fired/dropped from the exact same height and instant?

Can't answer the first bit, but the second Q. is NO. If I am reading the Q correctly, can I assume that you are in a balloon high above the desert looking down? The reason being that the bullet DROPPED downwards will accelerate to terminal velocity (t/v) and continue at this t/v rate until it hits the ground. However, the bullet FIRED downwards will decelerate, albeit slowly until it reaches t/v. Then it'll simply continue at this speed until it hits the ground. Clearly, the fired bullet has had an initial advantage that gravity couldn't prevent. But in either case, at 230g, I wouldn't try catching them!

Just me with my ex part-time Physics teachers hat on

But Peter, according to the theories...the bullets should be falling at the same speed...and we're only dealing with say, a meter. The forward movement shouldn't matter and the downward movement should be the same because of gravity. If you deal with a perfect vacuum and a perfect plain then in theory they should strike at the same time...? I too used to teach these things and the troops informed me I was teaching physics... Neat...

The first question depends on muzzle height when the bullet is fired. At 48" height, which should be the height of an M1 Thompson when you fir from the shoulder, the tables are available for bullet drop and trajectory...without getting a pencil sharpener out...

Quote:

---

Originally Posted by Peter Laidler

bullet FIRED downwards

---

The bullet is fired perfectly level not downward.

Level...RTFQ... Get your pencil out Peter...

Q1, How far will a .45 ACP travel before striking the ground if fired level from hip height?

Plugging some numbers, hip height? 1 meter perhaps, velocity of a .45 ACP, 230gr ball 270 m/s @ muzzle 5" test barrel.

Rate of fall for a .45 ACP round dropped at 1m:

Speed at impact:4.43 m/s
or 15.94 km/h
Time until impact: 0.45 s
Energy at impact: 0.15 joules

270*0.45s = 121.5m (not accounting for horizontal deceleration of the projectile, and subsequent reduction in travel range)

Due to the earth being spherical, the dropped round will travel a shorter vertical distance than the fired round, as optically level does not account for the geoid model. Even built level ground in not truly level, it is slightly curved. Rough math suggests the fired projectile will have to travel an additional 12 millimetres vertically to reach the ground.

Re-running the calculations shows this does not change the travel time to the nearest hundredth of a second.

Q2, Do they fall at the same rate?
This is a tricky bit to remember, however, I will say they should fall at the same rate, negating wind resistance on the projectile shape, both should accelerate vertically at -9.8 m/s2 at 1 m height terminal velocity will not yet be reached.

There is my mental exercise for the day, I am curious to see the answers, and gather what I've missed.

As we used to joke in the survey world, "F**k it, close enough".

Quote:

---

Originally Posted by WarPig1976

How far do you think a .45 ACP bullet will travel if the muzzle is perfectly level at firing at about waist level?

---

He meant distance from the firer...like 100m, 200m?

Quote:

---

Originally Posted by Sentryduty

negating wind resistance on the projectile shape,

---

The perfect plane, in a vacuum...things that can't physically be done. All theory...

Quote:

---

Originally Posted by browningautorifle

The perfect plane, in a vacuum...things that can't physically be done. All theory...

---

Indeed, it's a blackboard physics game, "if two identical snowflakes..."

To break the basic questions back down, I see: how far would a bullet travel on the level before plowing into the dirt? and does the action of firing a bullet perpendicular to the earth defy gravity?

Based on that breakdown, I say not more than 121.5 metres (based on my assumptions of mass etc) and NO shooting a bullet doesn't defy gravity. Shooting upwards only overcomes gravity.

Now I am reminded of the charts of sight adjustments based on shooting uphill vs downhill spring to mind and other tidbits of info, stuff I may never use again actually.

But I did quantrify my answer with an assuming question first. By LEVEL did he mean lever vertically or level horizontally? And he did ask if A bullet would.... When if he was meaning in relation to the first part of the Q, he should have said THE bullet. And I did explain the reason for answering the Q in the way it appeared to be asked.

Remember the old teaching basics. If a question can elicit a wrong answer, then the teacher is at fault.

Like 'Q...... what do tanks run on' A.Tracks. Or is it Roads or is it Petrol?

WTF is this debate about its self explanatory or am I being thick? I'm probably on my own as always! :surrender:

Quote:

---

Originally Posted by Gil Boyd

WTF is this debate about

---

If a paratrooper is dropped at the same time as a door bundle, which will hit the ground first?

Quote:

---

Originally Posted by browningautorifle

If a paratrooper is dropped at the same time as a door bundle, which will hit the ground first?

---

Entirely dependent on the air speed velocity of an unladen swallow.

This reminds me of physics 101 when I did that years ago.. The question as a child was what falls faster, ton of bricks or ton of feathers. Penny or a car.? Key to understand that earths gravity has same pull on everything Also Impt to understand the vacuum concept. True, everything is pulled with same force towards earths center, so; answer is bullet fired at perpendicular line to earth falls at same speed that it is dropped and lands at same time unless the ballistics of the projectile allows "flight" or rise like an Airplane. Or if something acts on the projectile like wind, rain, a body, leaf Etc. since we don't live in a vacuum, small atmospheric forces have some very little effect thus they land approx at same time but negligible in physical terms. Newton and his "Apple" helped this theory .

I know I hit the ground long before a heavy drop, and thank God for that, not something I looked forward too on many occasion, watching them coming in once we had hit the DZ............... probaly the most dangerous period in a Paratroopers life!!

Quote:

---

Originally Posted by Sentryduty

Entirely dependent on the air speed velocity of an unladen swallow.

---

African or European?

Quote:

---

Originally Posted by Gil Boyd

probaly the most dangerous period in a Paratroopers life!!

---

Specially if you were the first wave into the DZ and the second came early or you were slow clearing to the rally points. The crap that would rain down from machine guns to helmets to rucksacks...was shocking. If you were the smallest man you could jump the .30 cal and about 6 belts...they'd load you on the ramp with a forklift and throw you out like a door bundle. So, you'd hit the ground at about the speed of the .45 being fired straight down...but not land as nice.

Being dragged along the DZ unable to release is pretty scary......

Quote:

---

Originally Posted by browningautorifle

If a paratrooper is dropped at the same time as a door bundle, which will hit the ground first?

---

Both of them hit at the same time Jim if neither chutes open......

I guess in relation to Sentry's workings as he points out 9.8m/sec2 is the rate of gravity plus the friction of the air on the projectile will also decrease the range the bullet will travel in the horizontal plane before it hits the ground I was going along a harder question on which came first "The Chicken or the Egg?"
Your not alone Gil I will stand in your corner once I leave mine.......by the way Gil picked up an old Parker Hale shooting jacket patch the other day will get a pic of it and a few others I have for you to look at (We will look at them together in your corner so the others won't see)

Quote:

---

Originally Posted by CINDERS

Both of them hit at the same time Jim if neither chutes open......

---

And that brings us right back to the original question...

In theory, both will hit the ground (assuming it is level) at the same time. I remember 40+ years ago a physics experiment called the hunter and the monkey. The premise was a hunter aimed at a monkey hanging from the branch of a tree. Just as the hunter fired, the monkey let go. Would he hit the monkey? The practical session sadly didn't involve either a monkey or a rifle - just two ball bearings. One was held by a solenoid about 6 feet from the floor. Another was rolled along a horizontal ramp at the same height. A photo-switch at the end of the ramp de-energised the solenoid allowing both balls to drop at the same time (eventually, as sometimes the photo-switch failed, much to our amusement). Using a then state-of-the-art polaroid camera and a stroboscope in a darkened lab, it was shown that they both hit the floor simultaneously.

Ah.... happy days :)

Donald

Quote:

---

Originally Posted by Peter Laidler

Being dragged along the DZ unable to release is pretty scary......

---

So is looking up and seeing what looks like a line full of laundry instead of a canopy (or having a bag lock on a free fall jump) and having to go to the reserve with the thought, 'TOO LOW! TOO LOW!' screaming inside your head the whole time.

Quote:

---

Originally Posted by Peter Laidler

Being dragged along the DZ

---

Hopefully someone collapses your chute for you.

Quote:

---

Originally Posted by Paul S.

'TOO LOW!

---

And you hit like a ton of sh*t...when it opens at minimum. Nice.

Ok, The answer to the first question is roughly 360ft.
The answer to #2 is,,,Yes, both bullets hit the ground at the same.

The MythBusters ran the experiment. Here's the short version.

MythBusters Bullet Fired Dropped - YouTube

I don't get it- the bullets appeared to hit the floor at different times. Not very scientific to shrug off the 30 millisec or whatever difference. Not as impressive as the time they launched a water heater through the roof of a simulated apartment- now that was good!

I like the 100mph tape one picking up the car....

Quote:

---

Originally Posted by WarPig1976

The answer to #2 is,,,Yes, both bullets hit the ground at the same.

---

I could have saved you guys the conjecture here...I told you they did. But these guys aren't very scientific, their equipment comes from the salvation army...

My distance was only 30ft/10m past the supplied answer, given the number of assumed variables I had to use, I will call that a winner.