shooting at a moving target while in a moving car

[xXWildPonyXx]

ok so i was lying awake last night wondering about this shot i saw a officer make on one of those worlds wildest police videos where a cop shoots out a tired on a truck as they were doing like 60mph on the freeway. now i have done some sporting clays and when im standing still i aim a little before the clay bird and shoot and sometimes hit it. :-) but what about when both targets are moving the same speed? if i wanted to shoot out someones tire and were both doing 60mph would i point directly at the tire and shoot? or would i compensate for moving?

this is strickley hypothetical :-) i have no plans of shooting out anyones tires but it never hurts to know.... and hopefully this doesnt count as "trolling" i legitimately wanna know this

thanks

[fonz]

i would think you would still need to aim a little ahead of the tire due to wind force or some other physics type stuff. one i often wonder about while driving is about shooting straight ahead of you while doing highway speeds. such as shooting at something in front of you while driving 70 mph. i would think there would be a lot of force coming at the bullet and it would slow down rather quickly.

[Paradigm]

If you were behind the truck shooting straight ahead, there shouldn't be much of an issue.

If you were directly beside the truck, the 60mph crosswind would be an issue.

Proximity would factor into the equation. The greater the distance, the more wind resistance would affect the trajectory of the shot.

That's my guess. IANAP (I am not a physicist).

[Frenchy]

You would shoot the exact same way as if YOU where not moving at all. What I mean is that you would need to shoot ahead of the tire by how ever fast it would travel the distance to meet its intended target, and compensate for the wind that actually exists should you not be moving, just as you would in skeet.
Although you feel a wind resistance, it is an illusion effect by the fact that the car is moving against no wind, this being said, if there is no wind, there would be no wind effect.
The wind effect you feel outside a car is mainly caused by a stream of air rushing around the car. Right outside this stream, there is no more wind then there would be if you where standing still.
Naturally weight and speed will make a difference on how anything crosses that stream surrounding the car. For example if you took a helium balloon and threw it out of the car, it would be disturbed by the wind stream then float up as if there never was more wind then there exists outside that wind stream.
But if you took a marble, less wind resistance to cross that wind stream and a slingshot to propel it out the window, the marble would see very little effect.

When shooting a gun, the turbulence around the muzzle is already greater then the wind speed would be, one would believe because you are shooting at 90 degrees to the car the bullet would travel sideways a while, but the forward momentum of the bullet is not changed by the speed of the car. An example of this would be when you have some thing on the seat or dashboard that moves while the car turns a sharp corner. The item in question is not affected by a wind stream in the car, and moves freely from side to side having no momentum to the rear or front, the item is moving the exact same speed as the car, but if it is propelled outside the car, say like when people throw a bottle outside, the bottle does not continue at the same speed as the car because it is suddenly being slowed down by dropping to the ground, it will however continue in a forward trajectory bounce a few times and stop by friction to the ground. If you where to somehow reduce the friction, the item would follow the car at the exact same speed.
A good example of this would be in a total vacuum.
A bullet having much less trouble crossing the wind stream would travel past the slight stream around the car and to its intended target the same way it would if you where not moving. The forward velocity of the car having the same equal value seeing there is no ground to cause friction.
(When I say wind stream, the actual force is away from the car, not backwards as it is air rushing away from the car to allow passage of the car) What we perceive as air rushing past the car is actually the car rushing past the air. A very short distance from the car, there is no more wind then there would be should you be standing still.

In short the wind we feel when sticking our hand outside a car, is not actual wind it is standing air that our hand is rushing through causing the illusion of wind. The actual air is not moving, we are moving through it.

[xXWildPonyXx]

thanks for the time you put into that response frenchy :-) gave you rep for that going to have to re-read that later when im more awake i hate this time changing crap

[Coops]

Ah. a math problem

Einstein spoke about "frames of reference". In this example, your frame of reference is a car moving at a constant velocity of 60 mph. To the observer inside the car, the truck is 10 feet away and not moving at all so it is a stationary target. A bullet fired from a gun inside the car will appear to travel 10 feet in a straight line to the tire of the truck.

To an observer on the side of the road, the bullet would seem to exit the muzzle and follow an angled path in a straight line starting from the car at the point it was fired and ending at the truck tire however many feet the truck had moved since the gun was fired. The sideways velocity of the bullet would be 60 mph.

With a hypothetical muzzle velocity of 1250 fps the bullet would cover 10 feet in .008 sec so the truck would have moved a little over 8 inches between the time the gun was fired and the time the bullet hits the tire.

(60 mph is 316800 feet per hour or 88 fps so the truck would have moved 88 x .008 = 0.7 feet or about 8.4 inches.)

This means to the observer on the side of the road, the bullet traveled not 10 feet but the length of the hypotenuse of a right triangle with sides of 10 feet and .7 feet. Which is 10.025 feet.

None of this takes wind into account. If the wind is blowing in the same direction as the car at 20 mph, then it will seem like a 40 mph headwind. if the car is headed into a 20 mph wind, it will seem like a 80 mph headwind. In dead calm to a stationary observer in the car, they are standing still and the wind is blowing at 60 from the front of the car to the back. Once the bullet leaves the gun, it will be subjected to this crosswind. However, since the bullet is only in the air 8 milliseconds, leading the target would not be advisable. In real life, turbulence from the vehicles is probably greater than the effect of wind, and again, in 0.008 sec there is not much time for the wind to act on the small cross section of the bullet.

[hornady]

On the History channel they had Army sniper training , and said the hardest part of Qualifying was hitting a target out of a Helicopter. And these guys have to be good to even get to the school

[wa3ra]

The problem with the chopper is that you have multiple directional changes going on (Gotta think in three dimensions!) and the distances are much greater, hundreds or even thousands of feet.

A bullet, even a depleted uranium .50 gets pushed all over the place...from the gunner's seat, the flow of tracers looks like a straight line, but to an observer, they are actually travelling in an arc!

In the real world, every xth round is a tracer, and you can 'walk' your fire onto target.

I figure the cop would miss the tire that he was shooting at, and accidentally hit one of the other ones...

[HiredGoon]

...
I figure the cop would miss the tire that he was shooting at, and accidentally hit one of the other ones...

And then say "Yeah, of course I was trying to hit that tire"!

[Pukindog]

You are going to have to lead the target. The farther the distance; the more of a lead. I have a little experience with aerial gunnery and I had to feed the deflection into the gunsight. Once the info was into the sight the computer took over; lead was automatically fed into the HUD. Hit the pickle and you connected. A target drone hit with 20mm rounds out of a M61A cannon is an awesome sight.

Jeff