I am doing a lab report for a lab I did in class. The lab is about sliding a mass (in this case a book) down an inclined plane. I collected the data and calculated the acceleration for the mass if it fall at 90 degrees. I have to do an analysis but I having some trouble answering these questions. 1. When I found the acceleration for the mass when it slides down at a 90 degree angle to be 16.9 m/s2. The acceleration of gravity of is 9.8 m/s2. So why isn't this the value of 9.8 m/s2? Is it because 16.9 m/s2 is the weight? 2. How do I find net force on a mass on an inclined plane? I'm pretty sure I have to use Newton's 2nd Law equation: F = ma. But do I use 9.8 m/s2 or 16.9 m/s2 for a?