How does the density of a medium affect the speed of a wave?

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.

In the first law of thermodynamics, triangle e=q-w, what does q stand for

Which of these is the best way to manage a natural resource