# Finding the Mass from an Acceleration vs Force graph

1. Jul 28, 2014

### Crovati

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.

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

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 = 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 a big error during the experiment?

2. Jul 28, 2014

### MrAnchovy

No, but it's pretty near 2 x 0.3836 kg. How did you get the acceleration?

3. Jul 28, 2014

### Crovati

We used a motion sensor which took the velocity/time for each trial. the Average acceleration I posted there is the average of 5 trials for each of the different acceleration masses.