Conceptual questions about projectile motion

[vivekfan]

Homework Statement

If the projectile is launched and lands at the same level. Then the angle is the same at launch and landing, correct? And if the projectile is launched from a different height, then the angle of launch is different than the angle of landing? In such a situation, if it says that a projectile hits the ground at an angle of 45 degrees, that tells you that final horizontal and vertical components are equal, right? But in calculating those components, you would still use the launch angle?

Homework Equations

x= vocos(theta)t
vfy= vosin(theta)-gt

The Attempt at a Solution

I have outlined my views above. I just need to confirm that I am thinking about the situations correctly.

 

[LowlyPion]

But in calculating those components, you would still use the launch angle?

Not unless it was landing at the same level it was launched at.

If the level is different then the horizontal component is the same, but the vertical component of velocity is necessarily different, meaning that the |v| and the angle are necessarily different from the original |v| and angle of launch.

 

[Delphi51]

Yes, I think all you wrote is correct.
The main thing in all these problems is to do the horizontal and vertical parts of the motion separately. Use x = vt horizontally and almost always y = volt + .5at^2 and Vy = Vo + at vertically.