Question regarding bullets vs. car

[mad_hatter]

Gang,

I am not a physics major. I never took it and I know little about it. I need your help in solving a friendly disagreement between a friend and myself. I know this is the place to find my answer. My friend says that the likelihood of a person dodging a bullet is the same as a person dodging a car. I say it is less likely that a person could dodge a bullet and more likely that they could get away from a car. Help. It has my curiosity up.

 

[JaredJames]

Assuming you know both are coming and where from, you have a better chance of getting out of the way of a car.

Assume a car is going at max 54m/s (120mph), that means if the driver is 100m away when you notice it you have just under 2 seconds to react. Average human reaction (including thinking) is around 0.2s.

Now, take a bullet. A rough minimum speed for a bullet is around 200m/s. That means, if the shooter is 100m away, you have 0.5s to react.

So it is far easier to evade a car at nearly full speed than it is to get out of the way of a bullet at near minimum speed.

Of course, chances are a car will be going significantly slower than that, at around 23m/s (50mph) giving you far more time to react (around 4 seconds) and a bullet average speed is around 400m/s, giving you far less time (around 0.2 seconds - or what equates to you being required to react perfectly otherwise you won't get out of the way).

 

[mad_hatter]

Thank you very much for your response. I thought as much (but you said it better than I ever could have).

 

[K^2]

It kind of depends on what you are actually dodging. Dodging an actual bullet on its way and on-target is pretty much impossible. You cannot move out of the way fast enough even if you know it's coming.

On the other hand, dodging from the person who is firing at you is entirely possible, and has nothing to do with the speed of the bullet. It's simply a reflex vs reflex. Whether it's going to be easier or harder than dodging a car will depend on the circumstance.

 

[JaredJames]

It kind of depends on what you are actually dodging. Dodging an actual bullet on its way and on-target is pretty much impossible. You cannot move out of the way fast enough even if you know it's coming.

On the other hand, dodging from the person who is firing at you is entirely possible, and has nothing to do with the speed of the bullet. It's simply a reflex vs reflex. Whether it's going to be easier or harder than dodging a car will depend on the circumstance.

That was my basic reasoning as well. Hence the rather stringent conditions I put on it.

Assuming no cover (you're in an open field), I'd still put the odds against you dodging a fairly competent marksman in comparison to your ability to dodge a car.

Even a poor marksman under the same conditions, the speed of the bullet means they only have to predict your movement for a very short period in order to get a shot within the target area (you) and render your ability to dodge irrelevant.

 

[K^2]

That's why I'm talking about the situation. If somebody catches you off guard and just starts shooting, unless you find cover, you're done. On the other hand, if somebody is keeping you at the gun point, you can exploit the ~.15s reaction delay and make the first shot a miss with almost certainty. With second shot, things go back to the previous scenario. Shooter can anticipate motion and you won't be able to dodge that. But if you are at near point-blank range, that one missed shot is really all you need. A spectator is unlikely to tell who moved first, either, so it can look like dodging a bullet. Fun thing to try if you are paintballing and aren't afraid to take one at short range.

 

[Lsos]

Another thing, you can actually see a car. If you try to dogde a bullet, are you actually evading it, or jumping in its way? You won't know (until it's too late).

 

[sophiecentaur]

If you were relying on hearing the gun go off then the bullet could have hit you before you heard the bang. The marksman could have a much better chance of following your evasive moves than the car driver, who might only have one chance of hitting you before you dodge up an alley.
There are so many practical details. . . . .

 

[mrspeedybob]

A car can come around for another pass until it runs out of gas. A bullet will only pass by once so I would say you are more likely to Dodge 1 bullet then 1 car.

 

[JaredJames]

A car can come around for another pass until it runs out of gas. A bullet will only pass by once so I would say you are more likely to Dodge 1 bullet then 1 car.

If we're allowing a car multiple passes, it's only fair the shooter has more than one round.

 

[pallidin]

If you are ever fired upon by a right-handed person using a hand-gun, QUICKLY MOVE TO YOUR RIGHT.
The dynamics of the traveling bullet within the the barrel of a hand gun and how a single hand holds the gun will cause the bullet to change from a "spot-on" hit.
For a shooter that is right-handed, the bullet will eject from the barrel slightly to the right. If YOU move to the right(which is opposite to them), your odds of being hit are less.

This would be opposite for left-hand shooters.