# Homework Help: What is the initial velocity of the ball just as it enters the screen?

1. Sep 30, 2015

### camp_loll

1. The problem statement, all variables and given/known data
What is the initial velocity of the ball just as it enters the screen?

The Job

Using your understanding of projectile motion along with some background research on video analysis, devise a way to find the initial velocity of the tennis ball in the video just as it enters the bottom left of the screen.

Important Information

There is some important information for you to consider when completing this project. The distance between the two vertical black lines in the video is 50 cm. The distance between the two horizontal black lines in the video is 50 cm; but do not assume the same scale for the horizontal as for the vertical. Also, the frame rate of the video is 30 frames per second. Assume that position (0, 0) is the bottom, left corner.

2. Relevant equations
v_f = v_i - gt
d = d(v_i + v_f)
d = v_ox(t)

3. The attempt at a solution
I solved the initial horizontal and initial horizontal velocity which are 3.13 m/s and 0.784 m/s, respectively. I need to calcute the direction and the angle.

2. Sep 30, 2015

### Staff: Mentor

Hi camp_loll, Welcome to Physics Forums.

Your "Attempt at a solution" is a problem statement, not an attempt.

Can you show us what you've tried?