It looks like everything is okay except for your acceleration value - why is your equation for acceleration -g/m?
If you look at your data, you will see that the object does move up before it goes down as it should. You have a typo in your 'Relevant Equations' section (what you have for...
It's possible t was already defined so that even though that part of your script should work, it is not changing the value of t(11). Try clearing the value first:
for i = 1:10
t(i) = i
Alternatively, you can use vectorized code:
t = 1:10;
This is cleaner, takes advantage of...
If you just look at A and C, you should see that vA=-vC. In other words, A and C move at the same speed and when A moves down, C moves up (and vice versa).
You might be able to see the relationship between B and see, but let's try it a little more analytically: Let's call yC the position of...