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Q & A: Parachutes and weight

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Most recent answer: 10/25/2016
Q:
Two people of different masses are skydiving. If both people open their parachutes at the exact same time and the parachutes are the exact same size, which person hits the ground first? The person with more mass or less mass? Or do they hit at the same time?
- Lincoln (age 17)
Toledo, OH
A:

Hi Lincoln,

 

If it were not for air resistance then then both of them would hit the ground at the same time, ala Galileo's experiment dropping a heavy and a light ball from the Leaning Tower of Pisa.  If there is air resistance then there exists a 'terminal velocity' which depends on the weight as well as an aerodynamic  factor.   If the parachutes are the same size then the heavier person will hit the ground first.

 

LeeH


(published on 03/06/2014)

Follow-Up #1: Forward velocity of a parachuter

Q:
How does a parachute retard the velocity of the jumper? I see how air resistance retards the vertical velocity, but what retards the initial horizonatl velocity (hundreds of miles per hour?
- len (age >90)
Chevy Chase, MD, US
A:

Air resistance kills the forward velocity too, even before the parachute is deployed. A human parachuter is much less aerodyanmic than an airplane and has no thrust to maintain forward velocity. If there is sufficient altitude, parachuters usually wait a while after jumping to lose some of that forward velocity before they deploy the parachute.

Rebecca H.


(published on 10/25/2016)

Follow-up on this answer.