# Angle of Projectile

1. Sep 23, 2013

### physicsnobrain

1. The problem statement, all variables and given/known data
A golf ball is hit from the ground into a building window 50m high and 50m away from starting point. Find the initial angle.

3. The attempt at a solution
I will work backwards for this question. I assume that the final y velocity (Vy) is 0m/s.

the first equation I do is: Vy^2= Viy^2 + 2ay(y)
I solve this equation for Viy and I get 31.32m/s.

Next I use the equation: Vy = Viy + ayt
I solve this equation for time and I get 3.192s.

Next I use d = vt and in respects to x. I solve for v (being the initial x velocity). For this I get Vix to be 15.66m/s.

Now I have initial x and y velocity and use inverse tan to solve for angle. I get the initial angle to be: 63 degrees.

Are my numbers and method correct?

Last edited: Sep 23, 2013
2. Sep 23, 2013

### physicsnobrain

I believe my steps are correct.

Last edited: Sep 23, 2013
3. Sep 23, 2013

### voko

Why do you assume that the final vertical velocity is zero?

4. Sep 23, 2013

### physicsnobrain

The final y velocity I assume to be zero. I forgot to add in a part where it said that it hit the window at its max height of motion.

Given these circumstances I am correct, no?

5. Sep 23, 2013

### voko

With the clarification, your solution is correct.

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