Impact formula - Page 5

1. ## Re: Impact formula

If you fire from West to East your 1,200 feet per second muzzle velocity round will actually be moving at approxiamtely 2,500 feet per second on average around the earths axis depending on how far or near you are to the equator. If you fire from East to West your 1,200 feet per second muzzle velocity round will be moving only 100 feet per second in the opposite direction in which you fired it around the earths axis.

Sincerely,

William McCormick

2. ## Re: Impact formula

Originally Posted by Insaneride
William McCormick, the gyro effect does have an effect on the bullet but gravity remains the same. You care to further explain
I posted at the end of the thread about escape velocity. Firing East to West as opposed to West to East.

Sincerely,

William McCormick

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## Re: Impact formula

Originally Posted by Insaneride
The Earth's escape velocity is 25,030 miles per hour or 3,700 feet per second. Ironically, the Earth has a circumference of approximately 25,000 miles or the escape velocity in mph. This irony Probly doesn't apply using the metric system tho.
William McCormick, I think you were referring to my math and yes I got a decimal place wrong. The escape velocity should be 37,000 feet per second to escape Erth's gravity.

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## Re: Impact formula

Originally Posted by William McCormick
If you fire from West to East your 1,200 feet per second muzzle velocity round will actually be moving at approxiamtely 2,500 feet per second on average around the earths axis depending on how far or near you are to the equator. If you fire from East to West your 1,200 feet per second muzzle velocity round will be moving only 100 feet per second in the opposite direction in which you fired it around the earths axis.

Sincerely,

William McCormick
I see what you are saying but, what if you are driving east to west or vice versa, would that logic still apply? What if you threw a ball out the window while moving at 60mph traveling west, would the ball be traveling in negative miles per hour?

5. ## Re: Impact formula

Originally Posted by Insaneride
I see what you are saying but, what if you are driving east to west or vice versa, would that logic still apply? What if you threw a ball out the window while moving at 60mph traveling west, would the ball be traveling in negative miles per hour?
Yes the ball thrown east to west is traveling at negative 1,100 to 1,300 feet per second around the earths axis, on average depening on where you are, depending on how you average it, like most square feet of the earths surface or by the distance between poles and the equator.

Sincerely,

William McCormick

6. ## Re: Impact formula

I actually had the same question twice when I went to college.
I think you'll find that his textbook contains questions similar to below.

First time it was an arrow aimed directly at the monkey. In other words, no arc for proper shot placement.
In this slower scenario it's easier to visualize that gravity will affect both monkey and arrow over what ever time period it takes the arrow to get to the monkey.
Other possible variables are also neglected in this simplistic style question.

The second time it was a bullet. Also aimed directly with no arc for proper shot placement.
The time is much shorter, but to the same end.
Again, any other possible variables are neglected.

An additional question, preceding the other two, was the classic:
"Which bullet hits the ground first? One aimed parallel to the Earth, or one dropped at the same time as the other is fired."

Now, in my opinion, this question has to neglect the curvature of the Earth to assume a bullet could be fired "parallel."

The wording of the question is critical.

It's very common for students to "read into" a question based on personal tangible experience, instead of taking the beginning fundamental questions at face value.

This is where the teacher's pre-loading of the thought process is important. Students have to be made to understand that math/physics always starts with the fundamental style questions before adding in the complexity of additional variables.

If the teacher does not do this, students can easily misunderstand what is being asked.
I always sighted at 50 yards for my 30-06 rifle, at 100 yards I would be slightly high, at 200 I would always be high and to the right. At three hundres hards I was almost dead on maybe slightly high and at four hundred I was dead on.

Sincerely,

William McCormick

7. ## Re: Impact formula

When shooting chrome hub caps laid against a sand wall, at 400 yards, they would jump up and spin, like flipping a coin. I would fire while they were in the air and aim under them, and hit them every time. But I had the best Simmons scope I could buy at the time. The lens was large in diameter. So it let in a lot of light and gave a fantastic field of view even when zooming in, so you would not lose sight of the moving target. A friend and Marine weapons expert, checked it out one day, and he just kept laughing as he was targeting things in dark places.

Sincerely,

William McCormick

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## Re: Impact formula

Originally Posted by William McCormick
When shooting chrome hub caps laid against a sand wall, at 400 yards, they would jump up and spin, like flipping a coin. I would fire while they were in the air and aim under them, and hit them every time. But I had the best Simmons scope I could buy at the time. The lens was large in diameter. So it let in a lot of light and gave a fantastic field of view even when zooming in, so you would not lose sight of the moving target. A friend and Marine weapons expert, checked it out one day, and he just kept laughing as he was targeting things in dark places.

Sincerely,

William McCormick
You know the surface of the earth at sea level is about 4000 miles/ or 6400Km (metric) from the center of our Earth? Doesn't that gear things down?

At Equator
Last edited by Insaneride; 06-23-2019 at 10:18 PM. Reason: At Equator tho

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## Re: Impact formula

Does a bird flying east flap its wings more or less to go the same speed as a bird flying west??

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## Re: Impact formula

Depends on the wind speed..... and if you mean airspeed or groundspeed or..... earth rotationally corrected ground speed

Wow!!

12. ## Re: Impact formula

Originally Posted by Willie B
I know this teacher was unwilling to entertain the concept that bullets don't fall short range because sights compensate. She was upset that a student understood where she did not. Someone had to pay. Despite having time to research, she still considered his claim that bores are not parallel to sights to be "ridiculous" She carried her presumption to the parent conference still willing to fight it out. She was wrong, and unwilling to admit it.

What amazes me is that hundreds of students before Zack never challenged her.

I can prove that 10 bullets fired from a rifle at 100 yards can hit near bullseye showing little evidence of the effects of gravity. A monkey will fall, few will argue.
I used to get escorted to the principles office weekly, haha, for telling the teacher she did not know what she was teaching. Most teachers live in a magic bubble where only their reality is real. She got so mad one time she used derogatory words to describe me to the other students that she asked to explain the problem to me. When she got back four different and wrong answers she realized she not only did not understand but she had caused a misunderstanding in the other kids as well. Then she used a derogatory term to describe them. I think it was with fractions and she did not know why she was inverting the fraction in some cases and not others and where to put the variable. It was a bit disheartening. The good thing was I knew she didn't get a real education, so I just dismissed here, some kids got messed up, they were never the smiling kid with their hand up again. So sad not the teacher's fault either, she was given a vacuum of knowledge and forced to memorize and fill that vacuum with anything they gave her, to get her glorious degree.

Sincerely,

William McCormick

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