**Notes for teachers and learners who would like to use this TRZ file.**

The fy is parameterize for the ease of modelling.

m = mass of human body

A_h = surface area of human body

A_p = surface area of parachute

g at 2000 m height

d = density of air

Cd = drag coefficient of human body

Cd2 = drag coefficient of parachute

g2 = g near surface of Earth

T – duration for parachute opening in Model A

Model
A(Red): Parachute opens slowly over T seconds

Fy function:

if(t<35,m*g-A_h*0.5*d*Cd*vy^2,if(t<35+T,m*g-0.5*d*Cd2*(A_h+(t-35)/T*A_p)*vy^2,if(t<55,m*g-0.5*d*Cd2*(A_h+A_p)*vy^2,if(vy>0,-m*g,0))))

Model
B(Blue): Parachute opens fully
immediately

Fy function:

if(t<35,m*g-A_h*0.5*d*Cd*vy^2,if(t<55,m*g-0.5*d*Cd2*A_p*vy^2,if(vy>0,-m*g,0)))

Velocity-time graph for Model A:

Velocity-time graph for Model B:

Comparison of Velocity-time graph for Model A & B:

Acceleration-time
graph - Model B compared to Model A

Model B has a deceleration of 17

*g*, while Model A’s deceleration is 3.1*g*.
I think it is a bad idea to open the parachute
immediate while the parachutist is falling at 40 m/s. In real life, according
to a Discovery Education Channel video (https://www.youtube.com/watch?v=ur40O6nQHsw),
the parachute takes about 2-3 seconds to open fully.

__Ideas for teaching and demonstration:__

Adjust the
parameters and compare the velocity-time graph and acceleration-time graph.

You may find the free TRACKER Software at http://www.cabrillo.edu/~dbrown/tracker/

Related Singapore O
Level Physics question:

**5058/2010/P1 Q3**
It looks so fun! I am Passionate lover of skydiving, so thanks for sharing! Must visit to take your first ride beyond skies.. Skydiving

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