Parachutist freefalling question

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The discussion focuses on the mathematical modeling of a parachutist's freefall after deploying a parachute. The differential equation governing the velocity is established as dv/dt = g - kv, leading to the solution v(t) = (g/k) - ((g - v_0 k)/k)e^{-kt}. The user seeks guidance on deriving the displacement function x(t) from the velocity function v(t), noting that the distance traveled is the integral of v(t). A correction is made regarding the initial equation, stating it should be dv/dt = -(k/m)v.

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http://dl.dropbox.com/u/33103477/parachutist.png

(This is from a mathematics not physics exam)

Well what I've done, is to compose the equation describing the velocity of the parachute once it has opened. I did this by setting up the differential equation as:

\frac{dv}{dt} = g-kv

I solved that to get:

v = \frac{g}{k} - \frac{Ce^{-kt}}{k}

Now the parachutist was traveling at v_0 when it deployed so I can say V(0)=v_0

hence solving I got:

v(t)= \frac{g}{k} - \frac{g-v_0k}{k}e^{-kt}

Now the point is If I know how far from the ground the parachute opened I can figure out the distance traveled since the parachute was opened ?

I'm confused so any direction on how I should get to x(t) from v(t) would be useful.
 
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The distance traveled is the integral of v(t). (V, the velocity, is the derivative of the displacement v=dx/dt. The parachutist travels vertically downward, so the displacement is the same as the distance traveled here.)

You made a small error in the first equation: dv/dt=-(k/m)v.

ehild
 
Last edited:

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