Downward trajecting bullet gain speed?

[Bang]

Shooting a bullet upward, perpendicular to earth' gravitational pull, the bullet eventually ceases linear motion as it is overcome by gravity (skipping G1 and such for this question). Firing a bullet horizontal to earth gravitational force, the bullet will be pulled to earth. Now the crux of this question: when a bullet begins to drop from the extended bore axis and is essentially falling to earth, does gravitational pull during that fall make the bullet speed up a bit?

[streaker69]

Damn, that spirit of wakefield is still running around here.

[sprrdhawk44]

When you throw a baseball to a catcher, does it gain speed toward the end of its journey?

[twency]

Shooting a bullet upward, perpendicular to earth' gravitational pull, the bullet eventually ceases linear motion as it is overcome by gravity (skipping G1 and such for this question). Firing a bullet horizontal to earth gravitational force, the bullet will be pulled to earth. Now the crux of this question: when a bullet begins to drop from the extended bore axis and is essentially falling to earth, does gravitational pull during that fall make the bullet speed up a bit?

A horizontally fired bullet (or one fired below horizontal) will continually accelerate downward from the instant it leaves the bore until it either achieves terminal velocity under local conditions or is impeded in its path (by the ground, a target, or whatever)

[twency]

When you throw a baseball to a catcher, does it gain speed toward the end of its journey?

If the ball leaves your hand in a path horizontal to the earth (or below horizontal), yes. It will gain downward speed as it flies and consequently land lower than the point from which it started. Assuming terminal velocity isn't reached, which it probably won't be.

It loses horizontal speed due to air resistance, but gains vertical speed downward due to gravity.

[DavidTM]

Damn, that spirit of wakefield is still running around here.

Actually....it's the inverse proportion of the V-squared divided by pi, multiplied by the angle of the inverse co-axle equation of the vortex size of the bra cup speed when the last snap is undone. So....use safety glasses if she's got big one's.

Dave

[daschnoz]

In a perfect vacuum (space), yes - the bullet would pick up speed as gravity pulls it toward gravity's source.

Here on terra firma, speed lost to air resistance is a bigger issue. Any speed that may be gained is so minute compared to the bullet's speed, I don't think anyone is going to notice.

[Sshuker]

I would expect that even if fired straight down (from altitude of course) the bullet would be decelerating until it reached terminal velocity as I would expect even the lowest muzzle velocity to exceed terminal velocity from free-fall.

[twency]

In a perfect vacuum (space), yes - the bullet would pick up speed as gravity pulls it toward gravity's source.

Here on terra firma, speed lost to air resistance is a bigger issue. Any speed that may be gained is so minute compared to the bullet's speed, I don't think anyone is going to notice.

Air resistance in the vertical component is almost negligible for a small dense object like a bullet over the kind of scale we're thinking about here.

If you drop a bullet from your hand it quickly accelerates until it hits the floor very shortly after. The only meaningful difference if it starts with a strong horizontal component (ie. fired out of a gun) is it will hit the floor much farther away.

[sprrdhawk44]

If the ball leaves your hand in a path horizontal to the earth (or below horizontal), yes. It will gain downward speed as it flies and consequently land lower than the point from which it started. Assuming terminal velocity isn't reached, which it probably won't be.

It loses horizontal speed due to air resistance, but gains vertical speed downward due to gravity.

This reminds me of the physics class I had to take my junior year of college.

A particle is moving around the unit circle (the circle of radius 1 centered at the origin). At the point (0.6,0.8) the particle has horizontal velocity dx/dt=3. What is its vertical velocity dy/dt at that point?




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