apply friction a rough surface cardboard for example, the rougher it is the slower the ball will roll but to much friction and it will stop altogether.
how does increasing the height of a ramp affect how far a ball rolls down the ramp
Hmm. . . You can't modify the ball or the ramp. Those are two constraints that don't leave much room for improvement. Is changing the pitch angle of the ramp allowed? I suppose not. How about moving the ramp into a vacuum chamber? If you place the ramp and ball in a vacuum chamber and purge the air, you will eliminate -- or at least greatly reduce -- the friction due to air resistance. In a vacuum, the ball should roll down the ramp faster. How about blowing the ball down the ramp? Get behind the ball and, once it's rolling, blow hard! Better yet, get a hair blow-dryer and really give it a boost.
increasing
no
A ramp exerts no force, just gravity.
Twice as long as it takes to roll halfway down the same ramp. Without knowing the size of the ball, and the length & angle of the ramp, thats the best I can tell you.
The material of the ramp, the volume of the ball, and the mass of the ball.
The small ball
"If the ramp is steeper than the ball will roll faster" can be observed during experiments. "Friction slowed the ball down" and "Gravity caused the ball's motion" are both conjectures (guesses).
The ball rolling down the ramp might not have had time to reach 9.8 m/s^2. Also the coefficient of kinetic friction might have been high for the surface of the ramp.
yes it does. i just did the experiment.
You can control a lot during this experiment. You can control the weight, size, and density of the ball and the angle of the ramp, to just name a few.