A ball is launched upward at a speed of 20 meters per second (m/s) from a 60-meter tall platform. The equation for the ball’s height (h in meters) at time t seconds after launch is h = -4.9t2 + 20t + 60. How long before the ball hits the ground? Include units of measurement.

Answer 1

just solve for t in
-4.9t^2 + 20t + 60 = 0