Question 1181717
the initial height is the constant 35 m in the equation.
after 1.5 seconds, h(1.5)=4.9*2.25+1.5+35=25.475 m
when hits water h(t)=0
so -4.9t^2+t+35=0 or 4.9t^2-t-35=0
t=(1/9.8)(1+/- sqrt(1+686)); sqrt(687)=26.21
t=27.21/9.8 for only positive root=2.78 seconds


{{{graph(300,300,-0.5,5,-15,40,-4.9x^2+x+35)}}}