It is an arc- properly called a parabola. The faster the bullet, the flatter the arc.
The barrel guides and accelerates the bullet out of the rifle, and imparts spin to the bullet to stabilize the bullet in flight.
A "tracer" bullet.
Yes
Use some software, there are free ballistics programs available on the internet. A bullet throughout it's flight is subjected to the constant force of gravity, an accleration of about 10m/s^2 downwards, so the total drop ends up being a function of flight time. A high velocity bullet drops less than a slower one at the same range because it reaches the target quicker and therefore spent less time dropping.
Assuming the bullet is fired from a gun, the bullet will move out of the bore with a high velocity and will immediately begin falling and decelerating. If the bore is rifled, the bullet will also rotate on its long axis (providing stability in flight).
If that is its direction of flight, yes.
Trajectory.
Known as the muzzle velocity, it is the fastest speed the bullet will have in flight.
line of flight, or you can also call it a parabolic arc.
Bullets fired from a rifled firearm should NOT tumble in flight. If they do so, it is a sign of problems. This may be caused by different matters that all relate to the rifling in the firearm, and the bullet. First is rifling is badly worn, if the bore is oversized for the bullet, or if rifling is badly fouled with lead/ jacketing metal/powder deposits, the bullet will not be gripped by the rifling and spun, and may not be stable in flight (tumbling) Try cleaning the bore properly, and check for excessive wear at the muzzle. The second condition is the wrong weight/length of bullet for the rate of twist of the rifling. A fast rate of twist, combined with a very fast bullet, MAY result in the bullet "stripping", and not being spun by the rifling. Or a very heavy, slow bullet may not be spun fast enough to stabilize the bullet. Most .22 rimfire rifles are rifled to shoot 40 grain bullets accurately. If loaded with a 60 grain bullet, such as the Aguilla 60 gr SSS, the bullet will not be stabilized, and may tumble in flight.
A