Initial Velocity Question

Ok So if I were to launch a waterballoon with a waterballoon launcher VERTICALLY , how could I find out the Initial Velocity With OUT a stop watch? My other supplies include a meter stick

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 Are you familiar with conservation of energy?
 This is for a lab at school and you get Extra Credit if you can figure out the first part without a stop watch. Would i have to weigh it? And sorry, im not familiar with conservation of energy

Initial Velocity Question

Ok, are you familiar with the equations of motion?

 I am familiar with the equations for angles ( sin, cos), displacement in X,Y , etc,, for constant/non constant velocities and Trajectories
 Look through them and try to find one that involves the parameters you think are going to be important and post it.
 This isnt really a homework question but w/e Thanks again
 Well if I am shooting an object vertically then Displacment X will be 0m, and Vy = Vo * sin(90) because the degrees will be 90 VFy = 0 m/s Thats about all the variables i know atm Im unsure of which equation to use
 Well, dont solve any equations yet, just look for some that might be useful, and well work from there.
 Would this work VFy^2 = VOy^2 + 2a*Displacment Y
 Aha, you are on to something. Keep going.
 Displacment Y = {(Vo^2+sin(2*angle)} / g Only other one i know that doesnt involve time
 where did this come from? You were on the right track before. Maybe you should take a closer look at your first equation.
 its equation for X or Y displacment I am looking for Initial Velocity (Vo) and those two are the only ones that do not include time because i wont have a stop watch when doing this experiment
 Yes, look at your first equation, and you tell me what each of those terms mean.
 VFy^2 = VOy^2 + 2a*Displacment Y I am looking for Initial Velocity and not just VOy Final Velocity of Y = is 0 m/s in this case VOy^2 = is unknown a = 9.81m/s^2 in this case Displacment Y = is also unknown

Ok, we need to get this terminology straight.

$$V_{fy}$$ means the final velocity in the y direction.

$$V_{oy}$$ means the initial velocity in the y direction.

Does this help at all?

 Final Velocity of Y = is 0 m/s in this case
Yes, that's correct. Now when does this occur?