homework and exercises - Determine acceleration from experiment (Newton 2nd Law)

I have done a physics experiment (setup below). And was asked to determine the experimental and theoretical acceleration.

The data I've got

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Ok, am I right to say

Experimental acceleration = $2(s_f - s_i) / t^2$

Theoratical acceleration = $m_2 \times 0.98 / m_1$

Then

Percentage discrepancy = $\frac{|(Experimental - Theoretical)|}{Theoretical} \times 100$%

Answer

If by $s_f$ and $s_i$ you mean the final and initial position, respectively --- so that $s_f-s_i$ is just $d$ in your table --- then yes, your experimental acceleration is right. As for your theoretical acceleration, it should be $\frac{9.8m_2}{m_1}$, not $0.98$ --- the acceleration due to gravity is $g=9.8$. I'm assuming you just made a typo. Your definition of percentage discrepancy is right.