thanks for any help, not too sure what it means when it asks for the equation of motion

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- Apr 23rd 2010, 10:11 AMhmmmmmotion under gravity
thanks for any help, not too sure what it means when it asks for the equation of motion

- Apr 23rd 2010, 12:03 PMHallsofIvy
mass*acceleration= force and here the force is gravity, downward, -mg and friction, $\displaystyle -\gamma v^3$ (- because the force is always opposing the motion).

$\displaystyle m\frac{dv}{dt}= -mg- \gamma v^3$. The "terminal velocity" is when dv/dt= 0.

To find the "equation of motion" solve that equation for v and then solve $\displaystyle \frac{dx}{dt}= v$ to get the height as a function of t.