A skydiver weighing 180lbs (including equipment) falls vertically downward from an altitude of 5000 ft and opens the parachute after 10 s of free fall. Assume that the force of air resistance, which is directed opposite to the velocity, is of magnitude .75|v| when the parachute is closed and is of magnitude 12|v| when the parachute is open, where velocity v is measured in ft/s.

Find the speed of the skydiver when the parachute opens.

Question

A skydiver weighing 180lbs (including equipment) falls vertically downward from an altitude of 5000 ft and opens the parachute after 10 s of free fall. Assume that the force of air resistance, which is directed opposite to the velocity, is of magnitude .75|v| when the parachute is closed and is of magnitude 12|v| when the parachute is open, where velocity v is measured in ft/s.

Find the speed of the skydiver when the parachute opens.

anonymous · Answer

m=180lbs, |dw:1381361061290:dw|
mg-.75v=ma
changes to differential eqn
now we are to differential eqn

anonymous · Answer

Okay. I'm just a bit confused since it's not in SI units haha. Pounds is already a unit of weight not mass, so is "mg" just 180?