This report should adhere to a more formal lab report structure. You can see what that entails here.
What factors could contribute to this sensitivity?
Report the difference between what you've experimentally measured and what the simulation predicted. Are they within the expected sensitivity of the instrument?
On one graph plot the experimental data from your table along with the analytical prediction of the function you found. Do they follow the same trend?
Your plots should like a section of a cosine function. We can make the data a little easier to work with by plotting the mass as function of the $\cos(b)$ instead. Plot the results (both experimental and anlytical) with the mass of $P_3$ on the vertical axis, and the $\cos(b)$ on the horizontal axis. This should be a linear line:
$$\textrm{if } h(x) = \cos(x) \; \textrm{and}\; f(x) = C \cos(x)$$ $$\Downarrow$$ $$f(x) = C \times h(x) \; \textrm{a linear function}$$Find the slope of your linear data and compare it to what the slope should be from your analytical equation. Does it differ from the analytically derived slope by less than the uncertainty? There are more details about this process here.
Give the details of this calculation and compare your analytical results with the the experimental results.
Draw a vector diagram that shows the table arrangement.