Problem 3 Solve the falling parachutist problem from Example 1.1 in your book 3

Question

Problem 3 Solve the falling parachutist problem from Example 1.1 in your book 3 ways: a) Write the entire code in a single program b) Use another M file c) Use a function file In the results document just provide the plot Hint: Refer to Section 2.5 in your book or the function example in the Lecture 1 folder. For those of you who do not have your book yet here is the problem statement: A parachutist of mass 68.1 kg jumps out of a stationary hot air balloon. The drag coefficient, c, is 12.5 kg. Compute the velocity prior to opening the chute using the equation below. v(t) = mg/c( 1 - e^-c/mt)

Explanation / Answer

Solution for Part 1:

m = 68.1;
g = 9.81;
c = 12.5;

t = [0 1 2 3 4 5 6 7 8 9];

v = ( (m*g) / c) * ( 1 - exp( -(c * t) / m) );

plot(t, v), xlabel('time(s)'), ylabel('velocity'), title('velocity graph');

Solution for part 2 :

Go to File (or Home in newer Matlab versions) - > New - > Script (or M file)

A new file will be opened.

1. Copy the entire code given in part 1 into the file.

2. Save the file with a name, lets say testfile.m

3. to run the .m file, just type testfile in matlab console.

4. Done, plot will be displayed in a figure.

Solution for part 3 :

Step 1 : Save the below code in a file and name it same as your function name. (in my case, it will be func_velo.m).

function [v] = func_velo(m, c, t);
% Matlab implementation of velocity function
%
%
% input: m : Mass
% c : drag coefficient
% t : time
%
%
% output: v : velocity
%
%

m = 68.1;
g = 9.81;
c = 12.5;

v = ( (m*g) / c) * ( 1 - exp( -(c * t) / m) );

Step 2 :

m = 68.1;

c = 12.5;

take variable t.

t = [0 1 2 3 4 5 6 7 8 9]; or t = [0 : 1 : 10]; where 0 is starting number, 1 is step size and 10 is maximum size.

then call the function

[v] = func_velo(m,c,t);

and finally

plot(t, v), xlabel('time(s)'), ylabel('velocity'), title('velocity graph');

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