% [reserve space for function call  ]

% *** set constants and initialize variables ***
    g = -9.8    % accel. of gravity, units m/s/s
    dt = 0.1;   % time step in seconds
    t(1) = 0;       % array ('vector') of times, first time in s
    y(1) = 14.1;    % array of heights, initial height in m
    v(1) = 0.0;     % array of velocities, initial velocity at start of drop
    m = 0.1;     %  mass of ball, in kg
    Ftot = m*g;  %  total force on ball w/o drag, in N
    % *** might need to put other things here to set up for drag ***

% ***  now set up for loop ***
for i=2:1000    % note were starting on the second step
    accel = Ftot/m; % this appears to be a constant, why put it here?
    v(i) = v(i-1) + accel*dt;  % next velocity, our equation A
    vavg = 0.5 * (v(i)+v(i-1));   % average v over step dt
    y(i) = y(i-1) + vavg*dt;    % next position, our eqn B
    t(i) = t(i-1) + dt;     % bookeeping, makes time vector
    if (y(i)<=0), break, end   % run without at first
end

%plot(t,y)
close all
plot(t,y,'k+')
grid on
xlabel('time (s)')
ylabel('height (m)')

figure(2)
plot(t,v,'k+')
grid on
xlabel('time (s)')
ylabel('velocity (m/s)')

g =

   -9.8000

Published with MATLAB® R2015a