Question 183304
{{{s=-16t^2+v*t+s[0]}}} Start with the given equation.



{{{s=-16t^2+64t+25}}} Plug in {{{v=64}}} (the initial velocity) and {{{s[0]=25}}} (the initial height)



So the equation that models this problem is {{{s=-16t^2+64t+25}}} 



a)


{{{s=-16t^2+64t+25}}} Start with the given equation.



{{{s=-16(1)^2+64(1)+25}}} Plug in {{{t=1}}}.



{{{s=-16(1)+64(1)+25}}} Square {{{1}}} to get {{{1}}}.



{{{s=-16+64(1)+25}}} Multiply {{{-16}}} and {{{1}}} to get {{{-16}}}.



{{{s=-16+64+25}}} Multiply {{{64}}} and {{{1}}} to get {{{64}}}.



{{{s=73}}} Combine like terms.



So after 1 second, the rock is 73 ft in the air.