A sky diver weighing 180lb falls vertically downward from an altitude of 5000ft, and opens the parachute after 10sec of free fall. Assume that the force of air resistance is 0.75|v| when the parachute is closed and 12|v| when the parachute is open, where the velocity v is measured in ft/sec.
a) Find the speed of the sky diver when the parachute opens
b) Find the distance fallen before the parachute opens
c)What is the limiting velocity V_l after the parachute opens?
d) determine how long the sky driver is in the air after the parachute opens
Please, help

Question

A sky diver weighing 180lb falls vertically downward from an altitude of 5000ft, and opens the parachute after 10sec of free fall. Assume that the force of air resistance is 0.75|v| when the parachute is closed and 12|v| when the parachute is open, where the velocity v is measured in ft/sec. 
a) Find the speed of the sky diver when the parachute opens
b) Find the distance fallen before the parachute opens
c)What is the limiting velocity V_l after the parachute opens?
d) determine how long the sky driver is in the air after the parachute opens
Please, help

loser66 · Answer

It's not physics; It's math, differential equations.

mertsj · Answer

Do you realize that I have not done DE since 1961?

mertsj · Answer

@satellite73

loser66 · Answer

@rperez36 this is from your class, too. help me back, friend

anonymous · Answer

yeah I got you let me draw it out

loser66 · Answer

the equation is $$m\frac {dV}{dt}= g - 0.75V\\frac{dV}{dt}+\frac{0.75}{m}V=g$$

anonymous · Answer

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