Velocity uncertainty

[Guest Another IB Victim]

Hi, need a little help with this IA thing.

Basically, the investigation was me dropping a ball from different heights on a ramp and I was looking at how velocity of the ball affects the horizontal distance travelled by the ball after leaving the ramp. For each height, I repeated the thing three times so I had 3 separate readings for each height. From this, I was able to work out the uncertainty (by doing average minus highest then average minus lowest and just taking the largest uncertainty) which was 2.8. However, I'm unsure of what my uncertainty, if there is any, in my velocity.

To calculate the velocity, I used the suvat equation: 2s/t = v (by rearranging s/t = v+u/2)

where s was always 1 since I kept the distance travelled by the ball be 1 metre always before launching off of the ramp. I measured the distance travelled by the ball after in mm if that helps.

Thanks