What equation do I use to find the initial velocity of an object?
You can use Velocity = Initial Velocity + Acceleration*Time
V=Vi + at
Or s = ut + 0.5at^2
or v^2 = u^2 + 2as
it depends on what you know already.
There is no equation "to find the initial velocity of an object".
Sorry -- that was a bit hasty. I guess there could be a problem that gave you final conditions and asked you to work backward to the initial conditions. As tyco05 said the equations you would use to do that would depend on what you already know so there is no equation in general "to find the initial velocity of an object".
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