a2+b2=c2? Gravity affecting a shot

[GoM_Coaster]

Hey all. So, gravity affects an angled shot less than a shot parallel with the Earth. So velocity increases, so we would expect POI to move higher. However, most discussions I see about shot angles use ye ole a2+b2=c2... while this accounts for the change in the distance to target (fundamentally important), I don't think it actually calculates the change in the effect of gravity. Probably the gravitation effect is so small it wouldn't come into play until tremendous distances. If this is the case, why are we talking about gravity when we are really thinking about distance? Am I thinking about this wrong?

 

[blkqi]

Rifleman's rule is to just use the horizontal component of the distance.

 

[TxxAgg]

Gravity is a constant.

The horizontal shot distance is what matters.

 

[GSPHUNTER]

I don't know how I ever hit anything.

 

[GoM_Coaster]

I don't know how I ever hit anything.View attachment 674657

I usually just use the old a2+b+ = c2 if I know elevation and distance to target I can solve leg b in my head. Though to find c, I use a range finder which has angle built in anyway! Really just something to think about...

 

[blkqi]

I usually just use the old a2+b+ = c2 if I know elevation and distance to target I can solve leg b in my head. Though to find c, I use a range finder which has angle built in anyway! Really just something to think about...

If your original question was about how rifleman's rules relates, theoretically, to the parameters of distance and gravity, it doesn't. It's an empirical approximation.

 

[roadrunner]

The bullet will also decelerate at a faster rate from drag (air resistance) than the effect gravity would have to achieve terminal velocity.

The effect gravity has is negligible, but as stated, is constant and has the same effect whether uphill, downhill, or sidehill.

 

[7mm-08]

You're overthinking this one, friend.

 

[tyco]

The longer a bullet spends in the air, the more of an impact gravity will have. Gravity is a constant, but is a constant acceleration, not velocity. Gravity is roughly 32 ft/sec/sec. So the velocity of gravity is ~0 ft/sec (and increasing) as the bullet is leaving the barrel and ~16 ft/sec (and increasing) at the end of the first second. Bullet drop due to gravity would be higher at the end of a bullet’s flight, even if there was no resistance/drag whatsoever, not the same.

 

[Catchfish]

I just get closer

 

[Durran87]

In simplified physics we teach constant velocity for the horizontal component as an approximation, so use the kinematic equation x=vt + x0 using the horizontal component for velocity which is a cosine function. The vertical component is accelerating so use x=1/2at^2 + v0t + x0 and v=at+ v0, using the sine component of the initial velocity and -9.8m/s^2. Projectile motion makes an upside down parabola.

 

[BRTreedogs]

I laze it with the br4,
dial
And watch bodies drop.

 

[Beendare]

Rifleman's rule is to just use the horizontal component of the distance.

Yep…same with an arrow

 

[7mm-08]

In simplified physics we teach constant velocity for the horizontal component as an approximation, so use the kinematic equation x=vt + x0 using the horizontal component for velocity which is a cosine function. The vertical component is accelerating so use x=1/2at^2 + v0t + x0 and v=at+ v0, using the sine component of the initial velocity and -9.8m/s^2. Projectile motion makes an upside down parabola.

I like it, but that hurt my brain...

 

[Pharmseller]

 

[Chuckin_Rocks]

I like it, but that hurt my brain...

Physics is hard, try this

Gun go bang, gravity pull bullet down. Go down take time, fast bullets not go down so much. Air slow bullet down, how much? Don't care, too many numbers for me.....Gravity always wins. If shot go up, gravity takes longer to win.

Source: Took two semesters of college physics so someone would pay me look at rocks.

In all seriousness though we just assume a constant velocity from the muzzle
Over time gravity exerts a constant force that pulls the projectile down, this causes a downward acceleration. With some assumptions of a horizontal shot, constant velocity, constant acceleration, no air resistance etc we can easily calculate when the projectile hits the ground level.

When we consider the angle of the shot we have to understand that gravity must now overcome the upward component of the bullets velocity. It has to slow the bullets upward velocity down and reverse it, the higher the angle the longer this takes and the less impact it has on poi when it reaches the target.

If you were able to fire at a target directly overhead the only bullet drop you would need to account for is when it came screaming back down at you.