Understanding orbital motion requires prior understanding of projectile motion (because it is a special
case) in which the free-fall component is perfectly synchronized with the motion of the projectile around a
spherical Earth. In other words, an object in orbit continues to fall, but it keeps "missing" the Earth. Like
any other object in free fall, a body in orbit is continually accelerated, but in this case, acceleration is
defined as a constant change in direction rather than a change in speed.