Can't seem to get the correct acceleration

azn4lyf89

From a position vs. time graph I calculated the slope of 2 tangent lines which is the velocity. The first slope was 390 cm/sec and the second slope was 486 cm/sec. Now to get the acceleration I thought I take difference of the velocities divided by the time interval 0.9 (1/60 sec) or 0.015sec. After calculations I got an acceleration of 6,400 cm/sec^2 which would be 64m/s^2. The only thing is that the acceleration should be close to 9.80m/s^2 because it was a free falling object and I need to find percent error. What am I doing wrong because I should be getting around 9.80m/s^2 and not such a large number like 64.

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Kurdt

Staff Emeritus
Gold Member
It might help if you could post the graph you're working from. From working out the difference of the slopes one gets an answer of 96 which would get you a reasonable answer if the time interval was 0.1s. Are you sure you're reading the graph scale correctly?

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