What is the best way to calculate or take into account air resistance? I have an assignment which goes as:

Drop an object by itself and with a parachute, calculate air resistance for the parachute. It is assumed the object itself has no air resistance

Im kinda confused how to proceed with this since we have no course text book and there are no lessons just assignments


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  • $\begingroup$ Is the mass of the object and parachute given? And surface area too? $\endgroup$ – TechDroid Mar 7 at 14:05
  • $\begingroup$ @TechDroid No values are given. We have to choose the object to drop and the chute ourselfs. The whole assignment is literally those two sentences $\endgroup$ – Slurba Mar 7 at 14:55
  • $\begingroup$ @YuriyS "the air resistance FORCE is proportional to SPEED of the object" No, for any experiment the OP is likely to do it is proportional to the square of the speed. See en.wikipedia.org/wiki/Drag_coefficient $\endgroup$ – alephzero Mar 7 at 15:59
  • $\begingroup$ @ Slurba. Does the answer below clear your disorientation on the subject? If so, you might as well give it the credit. $\endgroup$ – TechDroid Mar 7 at 17:00
  • $\begingroup$ @alephzero, thank you, I deleted my comments $\endgroup$ – Yuriy S Mar 7 at 17:18

Your teacher or professor that assigned the practical experiment to you wants to help you put air resistance into perspective, so you'll have to make a clear distinction between just the fall and the fall with parachute. If you can access a height of about 40 feet, this will be enough to provide the clearance to record the time efficiently and also provide a good difference between the two cases. Weigh the combined mass of mass+parachute+strings with a precise and sensitive weight meter. Drop the ordinary mass first (for reference) couple of times and average the time observed. Now do the same for the mass plus parachute and average also.

Air resistance is a negating force on a moving object, hence the difference in net force on the body without parachute and that with parachute is the air resistance force. Using $F=\frac {md}{t^2}$ you can calculate the net force on the mass with parachute and $F=9.8m$ for just the mass.

  • $\begingroup$ You don't need a height of 70 feet!! If you make a movie of the experiment with a cell phone a drop of 1 or 2 meters is plenty - even less, if you can take a slow-motion video. Not to mention that dropping things from a height of 70 feet is dangerous - people have been KILLED when hit by objects falling from less than that height. $\endgroup$ – alephzero Mar 7 at 16:07
  • $\begingroup$ Alright. Maybe I went a little overboard with the height thing, but consider the OP not having a slow-mo capability? And why the down vote exactly? $\endgroup$ – TechDroid Mar 7 at 16:14

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