Many of the lab on acceleration reports had the same old problem. You used the same data to form and confirm the equation. You need to test an equation against quantities derived independently of the equation you are seeking to confirm.
Consider the questions I asked you.
I asked you what the mass was. I asked you what the force was. What can you find from this information?
Next I asked you did the slope of the graph confirm a kinematic equation. Many of you said sure the slope = 2 a and then proceded to prove by showing how 2a = vf squared/delta x. This is not a laboratory proof it is a restatement of our theory. Then you calculated the slope and said it sure equaled 2a ( some actually dropped the 2 and said it equalled a) by comparing it with the a you found from the very graph the slope came from. This proves nothing except you can get the same answer from the same numbers. You must compare the a found from the slope to a from some other way of finding a. Now think about the first two questions above and if they offer another and independent way calculate a. Now if that other a and 1/2 the slope are equal, you can confirm the validity of our kinematics equation. Remember, this is physics. If nature does not confirm it, it isn't right.
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