Zero, Proof, Nature, Five Dimension, Black Hole.
also a,b is proportional constant and intercept coefficient. It’s not problem as long as you can true of each conditions that -4.00[h] on x axis as a start point time corresponds to 0.00 [km/h] on y axis, -2.00[h] is about 0.05[km/h], 0[h] is about 0.39[km/h], 2.00[h] is about 0.05[km/h], 4.00[h]