An object is propelled vertically upward with initial veloci

An object is propelled vertically upward with initial velocity of \'25 meters per second. The distance s. in meters, of the object from the ground after t seconds is s = -4.9t^2 + 25t. (a) At what time(s) will the object Ik* 5 meters above the ground? (b) At what time will the object be at its highest from the ground?

Solution

a. 5 m from the ground

5=-4.9t²+25t

4.9t²-25t+5=0

t=0.21secs,4.89secs

b. Highest point is at the vertex which is t=-b/2a

t=-25/2*(-4.9)=2.55secs

s=-4.9t²+25t=31.89m