Final answer:
US projectiles spin clockwise when viewed from the rear, and they exhibit the gyroscopic characteristic known as precession due to torque being perpendicular to angular momentum.
Step-by-step explanation:
The direction in which US projectiles spin as viewed from the rear is clockwise. This spinning action gives the projectile gyroscopic properties, specifically the characteristic known as precession. A gyroscope or a spinning projectile will not just topple over when subjected to a force; instead, it will precess around its vertical axis. This is due to the torque being perpendicular to the angular momentum. In the example given of a spinning top placed on a flat surface near Earth's surface, the top precesses around the vertical instead of falling over due to gravity, which is similar to the behavior of spinning projectiles.