/sci/ - Science & Math » Thread #12629595

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Anonymous Tue 26 Jan 10:10:21 2021 No.12629595 View Reply Original Report

Quoted By: >>12629648 >>12629650 >>12630698 >>12632307

If I were standing in the bed of a truck going 60mph and I fired a gun with a bullet speed of 700mph, would the bullet be travelling at 760mph or 700mph?
Alternatively if I shot the gun backwards off the truck would the bullet be travelling at 640mph?

And also, If I were to fire a bullet at the speed of light the same direction the truck is travelling, couldn't it theoretically be travelling the speed of light+60mph?

Anonymous

Anonymous Tue 26 Jan 2021 10:32:00 No.12629630 Report

Quoted By: >>12630504

1. Theoretically, that wouldn’t add up perfectly. The drag of the bullet be the truck would have to be measured and arguably the friction coefficient is better for the bullet than the truck to an exponential degree, not just adjusted for weight but the volume . A net drag test has to be done before we can find out so no it wouldn’t add up perfectly, I’m saying that essentially air drag can be represented by a curve so your answer would also depend on when you measure the bullets speed as it enters the gun. I suppose on balance it would be 760mph going backward.
When does it reach terminal velocity? Drag is a volumetric coefficient and therefore cannot be linearly rationalized

Anonymous

Anonymous Tue 26 Jan 2021 10:43:25 No.12629648 Report

Quoted By: >>12630504 >>12633760

>>12629595
Are you 10? What kind of retarded questions are these? First of all define a frame of reference for the velocities you mentioned.

Anonymous

Anonymous Tue 26 Jan 2021 10:45:00 No.12629650 Report

Quoted By:

>>12629595
I think this requires relativity. Not sure.

Anonymous

Anonymous Tue 26 Jan 2021 11:32:45 No.12629747 Report

Quoted By: >>12630504

Correct me if i'm wrong, but it depends on the perspective.
>the man on the truck
>outside observer

Anonymous

Anonymous Tue 26 Jan 2021 16:32:53 No.12630504 Report

Quoted By:

>>12629630
>>12629648
>>12629747
do not know

Anonymous

Anonymous Tue 26 Jan 2021 17:21:38 No.12630698 Report

Quoted By: >>12632319 >>12633760

>>12629595
frame of reference is the ground
that's what your truck is going 60 relative to
if you are on the truck and fire a bullet in the direction the truck is going
it's going to be going (ignoring things like air) 760 using GALILEAN RELATIVITY
actually it's going something like 759.999999 when you use SPECIAL RELATIVITY because velocities don't add
that "bullet" going at the speed of light c, let's just call it light because you have to have 0 mass to go that fast
when it fires from the truck, it goes c
if you decide to reattach your frame of reference to yourself instead of the ground, that light still goes c
the speed of light is the same in every reference frame
this experimental fact is the impetus for special relativity
mix in that gravity is indistinguishable from acceleration and you are on the road to general relativity

Anonymous

Anonymous Tue 26 Jan 2021 23:15:05 No.12632307 Report

Quoted By: >>12633760

>>12629595
>would the bullet be travelling at 760mph
since relativistic effects are neglible at this speed, the answer is yes

>And also, If I were to fire a bullet at the speed of light the same direction the truck is travelling, couldn't it theoretically be travelling the speed of light+60mph?
no it would be traveling at c, due to relativity in the reference frame of the truck, the bullet would be travelling at c-60mph, but from your persepctive on the truck it still looks like it's travelling at c because you are time dilated. Of course at 60mph the time dilation and other relativistic effects are not noticable for you or an outside observer and all the math and observations would match up with the (incorrect) newtonian equations for motion, that is v=a+b.

The correct equation is v=(a+b)/(1+ab/c^2)

where a is the speed of the truck and b is the speed of the bullet.

Anonymous

Anonymous Tue 26 Jan 2021 23:17:04 No.12632319 Report

Quoted By:

>>12630698
>>>/x/

Anonymous

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Anonymous Wed 27 Jan 2021 10:06:16 No.12633760 Report

Quoted By: >>12633799

>>12629648
>Are you 10?
No
>define a frame of reference
The ground the truck is moving across
>>12630698
>>12632307
But what about firing backwards? Would it be moving 640mph relative to the ground due to the truck speed taking 60mph off?

Anonymous

Anonymous Wed 27 Jan 2021 10:20:53 No.12633799 Report

Quoted By:

>>12633760
>The ground the truck is moving across
760

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