Projectile Motion Experimental Error

[realslow]

Homework Statement

We carried out an experiment where we launched a steel ball at different degrees. We then calculated the launch speeds for each launch angle. We got a percentage difference of 2.8% between the "most different" values. What are two qualitative reasons for this error?

Homework Equations

The Attempt at a Solution

For the calculations, we were told to ignore air drag. I think that is an error, but I'm not exactly sure because we did the experiment in the same place and environment. I probably need some clarification about air drag.
I also think the launcher was a problem because it didn't give us the most constant shots. It was one of those ones with a spring, and you had to manually work it.

 

[phinds]

We carried out an experiment where we launched a steel ball at different degrees. We then calculated the launch speeds for each launch angle.

[/QUOTE]
How did you do that? What did you base it on?

We got a percentage difference of 2.8% between the "most different" values. What are two qualitative reasons for this error?

[/QUOTE]
Well, you list one of them yourself, below

I also think the launcher was a problem because it didn't give us the most constant shots. It was one of those ones with a spring, and you had to manually work it.

Measurement error is another possible reason but it's hard to say since you have not said anything at all about how you measured anything.