# Kinematics in two dimensions lab question

1. Sep 29, 2011

### me56

1. The problem statement, all variables and given/known data

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.

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.

I copied and pasted the above from my lab. Let me explain what happens in the Lab. There is a video, about 2 seconds long. There is a tennis ball that bounces in the screen and then dissapears again in about 1.5 seconds. I need to find the initial velocity. There is x,y graph taped to a wall with the black tape marking where the black lines are located.

2. Relevant equations

I beleive I need to use the following equation:

v^2=v(i)^2+2ax
v(i)=initial velocity
a=-9.8

3. The attempt at a solution

I do not know how to solve the equation and what to do with the numbers that I have. Can somebody please give me a hint.

2. Sep 29, 2011

### Spinnor

Are you supposed to take measurements of the position of the ball in each frame of the video? Using the horizontal and vertical lines for reference you should be able to analyze each frame and get x and y coordinates for the balls center. Once you have the data you can do some calculations.

First you need to get some data and then share it with us.