How could you make a sound wave have a lower pitch

Which property of fossils allow scientists to determine the relative rock ages..

What is work? how much work is done to move an object 0 meters?

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.