BBC Focus Magazine

[erykpilat]

Pretend there is a sharpshooter in top of a building , 100m from the ground. If he shoots at his target which is 1km away, how will the coriolis effect alter the bullets path and why?

[Shadowwolf]

He must be using a high power rifle for that shot.

Now I'm guessing but I don't think that the Coriolis effect would have any effect on a fast moving small object like a bullet over a short distance and time. Wind speed and direction will be relevant and accounted for by marksmen but not the Coriolis effect which due to Terra's slow rotation is quite weak, and only relevant to large things like atmosphere or oceans.

[The Beige Avenger]

The long range snipers, for pinpoint accuracy, do indeed take the coriolis effect into account... we're talking very long range... 1km, maybe...

It concerns the relative velocity of the bullet and the Earth that is rotating beneath.

Imagine shooting something north as the earth rotates east - west, as it travels along the ground moves sideways beneath so you need to aim to hit the target where it will be and not where it was... whilst remembering that you are already imparting a horizontal component of velocity yourself so the effect is small and only significant at very long ballistic flight times.

[M Paul Lloyd]

Agree 100% with Mr.A there.

[Shadowwolf]

This one of those counter intuitive things?

You see I'd have thought that the bullet was part of the system and thus because it it small, traveling relatively short ranges and for very short periods of time would remain unaffected. Bit like the fly on a train who can move freely about without having to match the trains speed or slamming into the end because it flew against the direction of travel.

[M Paul Lloyd]

It is still part of the system but the rotation of the Earth is too so it has to be taken into account, thus it gains a small advantage if travelling with the planetary rotation and by the same measure loses the equivilent amount if travllling the other way.
Its like being on a train and throwing a ball down the carraige, it will appaer to make no difference to anyone on the train but to an outside observer the ball thrown in the same direction the train is travelling is going to be moving much faster than the one going the other way.

If the bullet/ball were not part of the system the opposite would occur.

The efffect is also more noticeable the nearer to the equator you are as the surafce speed of the Earth is at its greatest at around 1000 mph.

[The Beige Avenger]

This one of those counter intuitive things?

You see I'd have thought that the bullet was part of the system and thus because it it small, traveling relatively short ranges and for very short periods of time would remain unaffected. Bit like the fly on a train who can move freely about without having to match the trains speed or slamming into the end because it flew against the direction of travel.

If the train accelerates though, the fly will have issues... like the coffee in your cup. The Earth is accelerating always as it is rotating. When the bullet leaves the gun it travels straight in the x-y plane (no forces acting on it... ignoring "real life"), a force would need to act on the bullet to preserve its relative position.