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**1. The problem statement, all variables and given/known data**

What speed must a ball be thrown vertically to reach a max height of 70m?

**2. Relevant equations**

**3. The attempt at a solution**

I originally tried to find the velocity by the fact that the velocity of the ball must be zero at a height of 70 m, accounting for 9.8 m/s^2 acceleration due to gravity (which is negative in this case)

So, if the velocity is decreased by 9.8 m/s every second, and reaches 70 m at zero, then I could find that if I knew the time that the ball is in the air.

To find the time, I could use x=xo + vot + (1/2)at^2, but then I need initial velocity!

What formula am I missing?