**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**
Now this is very easy to

ReplyDeletewithdraw bitcoin from blockchainwallet to paypal account just in seconds. This website is providing you many features and facilities. This is best chance to register for free and get surprises from our company on this new year.