speed = -1000 / speed = -10
#1
#1
#1
#1
speed = 1000 / speed = 10
#2
#2
#2
#2
percentage = 0.5
speed = -1000 / speed = -5
#3
#3
#3
#3
percentage = 0.5
speed = 1000 / speed = 5
#4
#4
#4
#4