The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

Mattnall wrote:And don't forget that before firing, the bullet at the equator is travelling at approximately 1000 miles per hour relative to the Earth's centre (sidereal period of rotation), approximately 66,000mph relative to the sun and a whopping 1.2million mph relative to the background radiation of the cosmos.

Makes a 3000fps (approx. 2000mph) bullet travelling away from me seem quite insignificant in the grand scheme of things.

George G wrote:If you fire the bullet parallel to the axis of the Earth’s rotation then you are firing it either due north or south.

Only if you are firing it at right angles to the axis of the Earth’s rotation can you fire it in the opposite direction to which the Earth is spinning, when you will be firing it pointing due west.

The bullet will immediately begin to fall toward the ground under the force of gravity at an acceleration of 32 feet per second per second, and its velocity will reduce due to friction with the air.

There will be an acceleration to the left (in the northern hemisphere) due to Coriolis effect, but it is very small, of some significance with long range artillery shells, but negligible for rifle bullets.

George G wrote:

George G wrote:If you fire the bullet parallel to the axis of the Earth’s rotation then you are firing it either due north or south.

Only if you are firing it at right angles to the axis of the Earth’s rotation can you fire it in the opposite direction to which the Earth is spinning, when you will be firing it pointing due west.

The bullet will immediately begin to fall toward the ground under the force of gravity at an acceleration of 32 feet per second per second, and its velocity will reduce due to friction with the air.

There will be an acceleration to the left (in the northern hemisphere) due to Coriolis effect, but it is very small, of some significance with long range artillery shells, but negligible for rifle bullets.

I was wrong about the direction - In the northern hemisphere Coriolis effect causes an apparent deflection to the right.

I have also discovered this U-tube clip which seems to show that the effect is far from negligible with a rifle at 1000 yards.

https://www.youtube.com/watch?v=jX7dcl_ERNs

However I am not certain that what he is demonstrating is Coriolis effect as he does not mention latitude, and if Coriolis effect were the cause of the apparent bullet drop or high flying, one would also expect some deflection - unless he were on the equator or at a low latitude?