gy7 Jump to level 1 The position of an object falling from a cliff with respect to the ground is given by s(t) = -4.9t + 84 where t is in seconds and s (t) is in meters. After how many seconds does the object hit the ground? Ex: 1.23 seconds What is the instantaneous velocity when the object hits the ground? m/s What is the average velocity? m/s