A football is kicked into the air from an initial height of 3 feet. the height, in feet, of the football above the ground is given by s(t)=-16t^2+35t+3.
Where t is time in seconds and t>=0. which is closest to the time when the football will be 20ft above the ground??
A) 2.72 seconds
B) 0.73 seconds or 1.46 seconds
C) 0.53 seconds
D) 0.53 seconds or 2.72 seconds
We are given with the equation s(t) = -16t^2 + 35 t + 3. 3 refers to ft which is the iniital height of the football. In this case, to find the time when the height is 20. We substitute 20 to s(t) then get t. Via quadratic equation or using the calculator, the times are B. B) 0.73 seconds or 1.46 seconds.