# Theoretical Line

I have a lab question that states "does your experimental value agree with the theoretical line for projectile motion?" What is a theoretical line and how do I compare these value.

I thought a theoretical line is x=V(sq.root(2h/g)), but im not sure.

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Homework Helper
What value did you measure?

i measured the horizontal distance and and horizontal velocity.

Homework Helper
Touchme said:
i measured the horizontal distance and and horizontal velocity.
So, which is the equation of the displacement in the x-direction? Which is the equation of the horizontal component of velocity? Use these equations to compare your test results with the 'theoretical' values.

The problem is that the theoretical values are not given. All I have is the equation and a plot of my experimental values. How do I determine the theoretical line that I need to compare my values?

Homework Helper
Well, I guess you have a plot of your experimental values dependent on time, right? So, just plug the 'times' into the 'theoretical' equations and compare the results. I hope I'm not missing something big here.

It is not a plot dependent on time. The plot is x (distance) vs. horizontal velocity. I plugged the values into the equation above and compared the values. But, is there a way I can draw or determine the theoretical line?

Homework Helper
Touchme said:
It is not a plot dependent on time. The plot is x (distance) vs. horizontal velocity. I plugged the values into the equation above and compared the values. But, is there a way I can draw or determine the theoretical line?
Horizontal velocity is constant and equals vx = v0*cosA, where v0 is the initial velocity and A is its angle. Since it is constant during time, it is represented as a horizontal line in a t-vx coordinate system. Maybe this is what you mean by 'theoretical' line.

how is it represented in a X vs Vx coordinate system?