How did you manage to bend the acrylic?
Acrylic softens when heated, so there are possibilities there - either bending it over a suitable form, or vacuum forming. Or, if you have thin enough acrylic so it bends, just force it to conform to your wooden base and screw it down.
I believe the previous gravity vehicle competitors used a thin, flexible layer of acrylic and forced it to conform to the wooden base they were using.
So far, I was thinking of using sheet metal as the ramp surface so that I could laser engrave lines into it for rails of some sort. As for an adjustable ramp (assuming you meant adjustable height), that probably wouldn't be necessary this year, though it might be next year. You would likely want the vehicle to be as high up as possible to give it the most gravitational potential
I think sheet metal could work great for the surface material of your ramp given its properly implemented on your base ramp. I agree that an adjustable height may not be necessary this year, although could be useful. You can accomplish the same thing by just releasing your car from higher or lower heights on your ramp via using shorter or longer lengths of string for your your release mechanism so that your car hangs lower/higher on your ramp.
However, I don't necessarily agree that you want your vehicle to be as high up as possible. If you find that your car is simply going too fast/has too much momentum as it's exiting your ramp, you may wish to lower the height at which you release it to lower the gravitational potential energy it's starting off with. Alternatively, although mass ideally shouldn't affect the kinetic energy your vehicle has as it leaves the ramp (due to it cancelling out with mass in the formula for gravitational potential energy: mass * height * 9.8 = 0.5* mass * velocity^2
), you may wish to decrease the mass of your vehicle as it will still affect your momentum (p = mass * velocity
). Too much momentum and you may not be able to brake properly leading to worse accuracy scores. I believe I'll start off with more mass than I think I'll need and lower my mass from there until I find a good balance of momentum for accuracy to speed for timing.