This is part of a lab I have to do, where we did an experiment with a car on a track and a fan, increasing and decreasing the number of batteries in the car to see the effect on its acceleration. Another group of students did a similar experiment, only instead of varying the number of batteries in the fan they added the mass to the cart and measured the acceleration of the cart. There is a table of their data: mass (kg) acceleration (m/s^2) .535 .58 .735 .40 .935 .32 1.135 .24 1.335 .22 1.535 .18 First it asks to make a graph of acceleration vs 1/mass. I did this, although I don't know why it's 1/mass as opposed to just mass. Then it says: If the force of the fan is equal to the product of the mass of the cart and the acceleration of the cart (Force=massxacceleration), how would you find the force of the fan from your graph? What is the force of the fan used to collect this data? I used the equation given, Force=mass x acceleration and I made: acceleration = Force x 1/mass -- which I think is important here, since my graph is acceleration vs 1/mass, but I still can't figure out how this helps me. I figured out what the force is using this equation and the given data, and it averages out to be around .291, which is not the slope of the tangent line of my graph, and it's not the area under the graph. So, I'm pretty much stuck looking at the graph. I feel like I'm just missing something obvious. Help? Thanks!