asimnaseer wrote:
> The basic movement is as follows
>
> Ft = thrust
> A = acceleration
> Vi = Initial velocity
> Vf = final velocity
> Cf = friction constant
> Ff = friction force
> F = force on object
>
> so...
>
> Ff = - Vi * Cf
> F = Ft + Ff = Ft - Vi * Cf
> A = F / Mass
> Vf = Vi + A * timeStep
One nitpick, Ff is (-Vnow * Cf), not Vi. I.e., the friction is
dependent upon the current velocity, not just on the initial velocity.
> If I know my initial velocity, distance left to go and final velocity,
> how do I calculate the thrust ?
As others have said, it's a calculus problem if you want to solve it
exactly and with fixed values, you'll be integrating the velocity to
calculate the distance travelled and thereby solve for the force that is
desired.
Left unmentioned, though, is which, if any, of these values are allowed
to change? For example, if Ft can change over time, then you have many
possible solutions. Presumably Ft is bounded by some maximum value, but
you've still got a wide range of possibilities.
Also, if Ft can change over time, then you could presumably have
solution that isn't generated by an equation but rather by a simple
feedback mechanism. E.g. "am I going the target speed?" -> Yes: do
nothing, No: apply (maximum?) force. With the addition of drag or
friction, of course you'll probably want to maintain Ft equal to Ff once
you've reached your target velocity.
good luck,
-tom!
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