The formula you will be using to analyse your data is "f=ma", Or "force=mass x acceleration. 

The weight of the car is the mass, the acceleration is the speed the car rolls down the ramp. When you multiply these numbers together, you will have the force. 

You will need to collect your data and plot it in a chart where one veriable is force, and the other is the degree of the slope. 

PSPP

PSPP is a free statistics tool you can use for scientific experiments. It generates reports based on the data you enter. It also creates graphs which you can copy and paste into your reports.

Watch and read the links below to for a tutorial of how to use the program. 

Give yourself plenty of time to view the videos and really understand how to use the program. Remember, this program is what university students use. It is best to obtain an understanding of this program now, before you start VCE science or university science. 

Use this link to download the program. PSPP - GNU Project - Free Software Foundation