I have a problem with acceleration,please help~

I have a doubt, about the acceleration,please refer to my program for details…
According to the physical formula: v^2 - v0^2 = 2ax
In the program I set the acceleration to 200, the speed is -100, so the moving distance should be 25,but it just 20. After that, I tried multiple sets of data and found that there is a coefficient of 0.8.
is this a bug or sth else?
thank u ~

Then I tried it in the beta. there are still some errors.
According to the set value, its coordinates at the highest point should be 47, but it went to 45

I think it is perfect to multiply the acceleration by a factor of 0.8 on the basis of version 0.8.11