Hydraulics<span> are used in the braking </span>system<span> of a car. They cause a relatively small force from the driver's foot to be multiplied to produce a greater force, which acts equally on all four brake pads. ... The transmitted pressure acts on this larger area to produce a larger load force on the brake pads.
</span>i think they are helpful, it just depends what your using them for :D
Since the black pieces absorb light better than white pieces, the white pieces will reflect light better. But since color doesn't affect sound, the sound waves are reflected the same.