A stone is thrown vertically upward with a speed of 18.0 m/s. How fast is it moving when it reaches a height of 11.0m? How long does it take to reach the height?

Given: v0 = 18.0 m/s, y0=0m, yf=11m, g=-9.81 m/s^2

v0 = initial velocity, vf = final velocity, y0 = initial height, yf = final height, g = gravity, sqrt () = square root, ^2=squared

vf^2=v0^2 + (2) (g) (yf-y0)

vf^2 = (18.0 m/s) ^2 + (2) (-9.81 m/s^2) (11 m-0m)

vf^2=18.0 m/s) ^2 + (-19.62 m/s^2) (11 m)

vf^2 = (324 m^2/s^2) - (215.82 m^2/s^2)

vf^2=108.18 m^2/s^2

vf=sqrt (108.18 m^2/s^2)

vf=10.4 m/s