I am trying to derive the acceleration between 2 points. For example if I had (90.39, 44.99), (90.4, 44.97) and the time span was 0.1s. I get how to calculate the speed but how could I calculate the acceleration from this?
To clarify from the comments:
You can’t. You require information about how the journey progressed in terms of its velocity
Whilst this is a technicality, it is entirely correct - you would need to know the initial velocity or the final velocity in order to truly answer this question.
However, it seems implicit to take the initial velocity to be zero in this case - in which case we are solving for acceleration and so will use the equation: s = u*t + 1/2*a*t^2.
where: s = displacement, u = initial velocity, a = acceleration and t = time taken.
Displacement is calculated by finding the root of the sum of the squares of the differences between the x and y values for the coordinates you've posted. (a^2 +b^2 = c^2)
And from there, calculating the answer is trivial.
No, you cannot without further assumptions and information.
You can't even calculate the speed. You can only calculate the average speed and by the first theorem of calculus that the body would have this speed at least at one time frame, but can have different speeds otherwise.