What was the relationship tested in the running shoe ramp experiment?

[jefflincoln]

I'm writing a lab that pertains to a running shoes motion down a ramp and calculating the coefficient of static and kinetic friction. We placed a running shoe on a ramp and increased the ramps angle of inclination until the shoe began moving down the ramp.

1.Is it correct for me to say that as the angle of inclination increased the force of gravity parallel to the ramp increased, therefore the shoe accelerated in this direction when it outmatched the force of friction ?

2. what type of relationship was being tested in this lab?

 

[haruspex]

Yes, but there's a little more to it. As the ramp is tilted, what is happening to the normal force?