What does the slope of a force vs displacement graph represent for springs

For general projectile motion, when the projectile is at the highest point of its trajectory, its acceleration is zero? a)the horizontal and vertical components of its velocity are zero. b) its velocity is perpendicular to the acceleration. c)the horizontal component of its velocity is zero. d)its velocity and acceleration are both zero.

Which articulations allow for greatest range of motion?

Most short-period comets do not have randomly oriented orbits because