Help! Acceleration vs Force graph..What am I doing wrong?

I have to confirm newtons 2nd law via a track and trolley experiment



1. The problem statement, all variables and given/known data


The trolley’s mass is kept constant.

The weight of the cart (252g) plus two bar weights (500g) is = 752 grams, plus additional weights of either, 10g, 15g, 20g, 25g or 30g for the different trials.



The acceleration weights are:

25g

20g

15g

10g

5g

for the different trials.



We used a motion sensor and a software program to get ΔV/Δt.



This is what i got in the end...



Acceleration mass (g)--------Force (N)-----------Average acceleration ms-2



---------5-----------------------0.049---------------------0.10

---------10----------------------0.098---------------------0.22

---------15----------------------0.147---------------------0.36

---------20----------------------0.196---------------------0.44

---------25----------------------0.245---------------------0.63





2. Relevant equations




F=ma

a=(1/m)F



3. The attempt at a solution


I plotted an acceleration vs Force graph, which gave me slope=2.6. And I thought that since F=ma, then the slope would be 1/m, and m= 1/2.6 =0.3846... kg.

If i’m thinking correctly then this should be the value for the mass of the trolley (the cart+the bar weights+the additional weights+acceleration mass)



But when i add all of the components of the trolley’s mass I get 787g...which is nowhere near 0.3846... kg.



I’m not sure what i’m doing wrong, or if I’m going about solving this in completely the wrong way. Or maybe I made an error during the experiment?

I’m completely stuck now and don’t know how I can finish my report. I’de really love some help!

1. The problem statement, all variables and given/known data







2. Relevant equations







3. The attempt at a solution