# 2D projectile motion problem

1. Feb 18, 2013

### jklops686

1. The problem statement, all variables and given/known data
A Projectile is launched from the top of a 100m tower and falls 20m below the bottom of the tower and 90m away in the x direction. Time of flight is 6 seconds.

1. Find the x component of the velocity of the object when it strikes the ground.

2. Find the y-component of the inital velocity of the object.

2. Relevant equations
I tried using Δx=Vi,x(t) to solve for the x component of Vf (since the inital should be the same as the final). Then I did the same thing for the y component of Vi.

3. The attempt at a solution
I got 15m/s for the x component of Vf and I'm not sure if this is correct. For the y component of Vi I solved and got 20m/s. I used -120m for Δy and i'm not sure if this is right because in the picture it shows the projectile going up a little before it begins to go down 120m.

Any input would be greatly appreciated

2. Feb 18, 2013

### Toranc3

Yo I got 15m/s for x. My y was wrong sorry.

3. Feb 18, 2013

### tms

Don't forget that the y component of velocity is affected by gravity.

4. Feb 18, 2013

### Toranc3

What did you end up getting for the y?

5. Feb 18, 2013

### ehild

How is the displacement along y related to the time of flight?

ehild

6. Feb 18, 2013

### Toranc3

Yo i got this problem too. Is vy 9.43m/s?

7. Feb 18, 2013

### ehild

Excellent!

ehild

8. Feb 18, 2013

### Toranc3

Awesome thanks!

9. Feb 18, 2013

### jklops686

I got it. Wow, I don't know how I missed that. Maybe my brain was overloaded from studying all day and just farted. Thanks, though!