how to calculate a negative acceleration?

Question

I\'m implementing the scrolling behaviour of a touch screen UI but I\'m too tired in the moment to wrap my mind around some supposedly trivial piece of math:

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Answer 1

Seems like you are looking for deceleration which increases over time.

Try computing

Delta_v = -(A*t + B) , selecting reasonable constants A and B, which suit you.

t is the total time till that point.

Change your velocity by adding Delta_v.

This basically corresponds to linear negative acceleration.

You can basically select any function which increases over time (say f(t))

and compute

Delta_v = -f(t)

An appropriate choice for f(t) would give you the effect you desire.

Some examples you could use:

f(t) = At + B.
f(t) = A*exp(Bt)

Of course, you will have to play around a bit and try to figure out the right constants.