How to choose a formula?

Question

JavaScript

Hello everyone The
task is to animate the block
There is a distance S that the block must go in both directions
That is, the block must return to its original position
There is a speed V that smoothly decreases to zero ( cubic-bezier.com/#0,.67,.3, 1 )
The problem is that I didn’t study math well at school and now I can’t figure out how to correctly calculate the speed along the path of movement in order to have time to go S back and forth and not stand in the middle of the path
Great mathematicians, please help!

Answer 1

Time to stop will be t=v0/a Then the distance traveled will be S=v0*ta*t^2/2

Answer 2

S/V = T.
S = TV
V = S/T
V - speed
T - time
S - path
S

Answer 3

Does the block move in a straight line? Or fluctuating along a thread?