You can investigate how the size of the surface area affects friction by putting a single 500g mass on the friction block and finding the friction force. Now turn the block on its edge (reducing the surface area by
a factor of at least 4) and CAREFULLY place the 500g mass on the top edge. Measure the friction force.
Does the different surface area make a SIGNIFICANT difference? Note: you've changed the surface
area by 400%-500%.
Why do you think this may be?

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.