is it true that if you shoot a gun over a long range at a target you wld have to adjust aim for spin of earth.

Answer 1

For the dip of the bullet and the windage, but that would be all I believe. And this is generally done by the scope you would be using.
Interesting though.

Answer 2

I'm not entirely sure of this answer - but does seem logical to me:
You would need to adjust your aim more to compensate for gravity and the the curvature of the earth - however minute that be in relation to the size of the earth as a whole, rather than because the earth is spinning....
Gravity is obviously caused and affected by the spinning of the earth, however the obvious effect is so miniscule as to be invisible and unobvious(?) to the distance you could shoot a target. It would however have the effect of pulling down on the projectile, thereby causing it to arc and then gradually drop as the force of gravity outweighs the force of projection.
By the same token, because the earth's surface is curved (the earth being spherical), combined with the force of gravity, adjustment (again however miniscule) would need to be made to compensate for these two factors.

Answer 3

Whenever generating trajectories from a rotating reference frame, you must account for the Coriolis effect or else your projectile will end up "curving" (to the right in the northern hemisphere and to the left in the southern hemisphere). This effect has NOTHING TO DO with the curvature of the earth. It's PURELY because of the ROTATING reference frame.

Imagine a playground toy where children sit at the edge of a large circle that can rotate. If the circle is sitting still, if the child wants to toss a ball to the person directly across from them, the child just has to throw straight across. However, if the circle starts spinning CLOCKWISE, if the child throws striaght across, the other child will spin away from the previous destination. The ball will still hit the location where the child WAS, but from the point of view of sitting on the spinning circle, it will APPEAR like the ball CURVED to the RIGHT.

(if that example doesn't help you, think about being on a merry-go-round. If you try to toss a ball to someone away from you, your ball will appear to curve "away" from the person. However, it is actually that your ball went straight but the person moved away from the ball. You didn't notice the person moving because you were moving in the same rotational reference frame as the person)

(a final example: a rotating sprinkler. The water appears to "curve" away from it as it rotates. However, each droplet is actually going straight out. The droplets are just released as the sprinkler is rotating. From the sprinkler's point of view, it appears like the water is curving away from a straight trajectory. However, this is only because the sprinkler is rotating)

The same thing happens on earth. If you look "down" on the north pole, you see a spinning circle that looks just like the experiment above. Similarly, if a projectile takes off from one location heading for another location, while that projectile is in the air, the earth will cause the destination to "spin away" from the projectile. Thus, the projectile will "miss" its target and will APPEAR (to people on the spinning planet) to "curve" to the right.

Planes need to adjust for this when traveling to their destinations. They need to "pre curve" their trajectories so that they'll end up where they expect.

Take a look at the sources below. The second source (on the Foucault Pendulum) includes some graphics that may help you understand this effect. The third link (also on the Foucault pendulum) also provides some helpful animations.

Note that this effect has nothing to do with the curvature of the earth. It purely has to do with the fact that the earth is SPINNING. It's all about being on a rotating reference frame.

(in fact, Germans in WWII used knowledge of this effect to adjust how their long range shells were fired)

(note that in the case of a ballistic missile, you'll also have some curvature from the inertia of the missile as it gets whipped around from the centripetal acceleration due to gravity; for things that have a normal force exerted on them from the earth, this gets canceled out. See the "poleward force" references in the last source for more details)

Answer 4

no you do not. the bullet is rotating with the earth as it is fired. this is similar to throwing a ball while on a plane while flying. if you let the ball go it will not move towards the back of the plane due to the fact that it is travelling along with the plane. similarly you do not have to throw the ball with sufficient force so as to counteract the direction of travel of the plane. of course with a ball in outdoor conditions aerodynamics would need to be taken in to account. yet with a bullet air resistance will be a smaller a factor and in any case. the air through which the bullet is moving would also be spinning along with the earth.

also, to correct an earlier point. the spinning of the earth does not cause gravity. it does in fact oppose its effect. think of a drop of water on the outer surface of a football. if you spin the ball it is not held on it is flung away at a tangent.

Answer 5

There must be a difference, if the gun is fired eastwards or westwards the earth spins at about 1000 MPH at the equator, so there would be a 2000MPH difference in the speed or would there? Look at it this way escape velocity from earth is about 17000 MPH if it was with the spin it would be OK if it was against the spin it would not escape.

Answer 6

Yes

It's due to Coriolis Force, or the Coriolis Effect.

Applicable (so you'd notice) over long distances, a gunner must correct fall of shot to take account of the earth's rotation while the shell is in the air - otherwise called deflection.

Can't be sure of the amount, but I think it would be around 400 yards for a fifteen mile range, so applicable more for heavy artillery.

Answer 7

Yes it is true, the Coriolis effect as stated above.
Further reading A Short History of Nearly Everything by Bill Bryson; chapter 17 Into the Troposphere.

Answer 8

Not unless you plan on leaving the atmosphere.
Or you consider Wind to be the spin of the earth, which in a round about way it is. Wind is accounted for even over short distances.

Answer 9

The curviture of the earth might make a difference over a very long distance but in real life, gravity and wind resistance make more of an impact.
The spin of the earth will not have any effect.

Answer 10

Not sure about the spin of the earth, but as a bullet slows down it gradually drops to the ground.

Answer 11

No it is not true. No gun can fire far enough for the earth's spin to affect the fall of shot.