Projectile motion with non-constant air resistance












0















I need to simulate the projectile motion of a "Paris Cannon". I need to consider the air resistance changing according to the altitude with the following equation:



p = p0*exp(-y/y0)


where y0 = 1000m



And the drag is:



Fd = -0.5*C*p*A*v^2


So far, my code looks like this:



clc
clear
m = 94;
A = pi*(.21)^2;
C = .12;
p0 = 1.225;
g = 9.81;
%Initial Conditions
dt = .001;
x(1) = 0;
y(1) = 0;
v = 10000;
angle = 20;
vx = v*cosd(angle)
vy = v*sind(angle);
t(1) = 0 ;
i = 1;
y0 = 1000;
while min(y)> -.001
p = p0*exp(-y/y0)
Drag = p*C*A/2*v^2
ax = -(Drag/m)*(vx*vx+vy*vy)^0.5*vx;
ay = -g-(Drag/m)*(vx*vx+vy*vy)^0.5*vy;
vx = vx+ax*dt;
vy = vy+ay*dt;
x(i+1) = x(i)+vx*dt+.5*ax*dt^2;
y(i+1) = y(i)+vy*dt+.5*ay*dt^2;
t(i+1) = t(i)+dt;
i = i+1;
end
plot(x,y,'-')
xlabel('x distance (m)')
ylabel('y distance (m)')
pause(0.001);


I cannot get the correct simulation here. If I take drag as constant and place it in initial conditions, it works fine. But when I put it in the while loop, the whole simulation gives me absolute nonsense. I would appreciate your help.










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    0















    I need to simulate the projectile motion of a "Paris Cannon". I need to consider the air resistance changing according to the altitude with the following equation:



    p = p0*exp(-y/y0)


    where y0 = 1000m



    And the drag is:



    Fd = -0.5*C*p*A*v^2


    So far, my code looks like this:



    clc
    clear
    m = 94;
    A = pi*(.21)^2;
    C = .12;
    p0 = 1.225;
    g = 9.81;
    %Initial Conditions
    dt = .001;
    x(1) = 0;
    y(1) = 0;
    v = 10000;
    angle = 20;
    vx = v*cosd(angle)
    vy = v*sind(angle);
    t(1) = 0 ;
    i = 1;
    y0 = 1000;
    while min(y)> -.001
    p = p0*exp(-y/y0)
    Drag = p*C*A/2*v^2
    ax = -(Drag/m)*(vx*vx+vy*vy)^0.5*vx;
    ay = -g-(Drag/m)*(vx*vx+vy*vy)^0.5*vy;
    vx = vx+ax*dt;
    vy = vy+ay*dt;
    x(i+1) = x(i)+vx*dt+.5*ax*dt^2;
    y(i+1) = y(i)+vy*dt+.5*ay*dt^2;
    t(i+1) = t(i)+dt;
    i = i+1;
    end
    plot(x,y,'-')
    xlabel('x distance (m)')
    ylabel('y distance (m)')
    pause(0.001);


    I cannot get the correct simulation here. If I take drag as constant and place it in initial conditions, it works fine. But when I put it in the while loop, the whole simulation gives me absolute nonsense. I would appreciate your help.










    share|improve this question



























      0












      0








      0








      I need to simulate the projectile motion of a "Paris Cannon". I need to consider the air resistance changing according to the altitude with the following equation:



      p = p0*exp(-y/y0)


      where y0 = 1000m



      And the drag is:



      Fd = -0.5*C*p*A*v^2


      So far, my code looks like this:



      clc
      clear
      m = 94;
      A = pi*(.21)^2;
      C = .12;
      p0 = 1.225;
      g = 9.81;
      %Initial Conditions
      dt = .001;
      x(1) = 0;
      y(1) = 0;
      v = 10000;
      angle = 20;
      vx = v*cosd(angle)
      vy = v*sind(angle);
      t(1) = 0 ;
      i = 1;
      y0 = 1000;
      while min(y)> -.001
      p = p0*exp(-y/y0)
      Drag = p*C*A/2*v^2
      ax = -(Drag/m)*(vx*vx+vy*vy)^0.5*vx;
      ay = -g-(Drag/m)*(vx*vx+vy*vy)^0.5*vy;
      vx = vx+ax*dt;
      vy = vy+ay*dt;
      x(i+1) = x(i)+vx*dt+.5*ax*dt^2;
      y(i+1) = y(i)+vy*dt+.5*ay*dt^2;
      t(i+1) = t(i)+dt;
      i = i+1;
      end
      plot(x,y,'-')
      xlabel('x distance (m)')
      ylabel('y distance (m)')
      pause(0.001);


      I cannot get the correct simulation here. If I take drag as constant and place it in initial conditions, it works fine. But when I put it in the while loop, the whole simulation gives me absolute nonsense. I would appreciate your help.










      share|improve this question
















      I need to simulate the projectile motion of a "Paris Cannon". I need to consider the air resistance changing according to the altitude with the following equation:



      p = p0*exp(-y/y0)


      where y0 = 1000m



      And the drag is:



      Fd = -0.5*C*p*A*v^2


      So far, my code looks like this:



      clc
      clear
      m = 94;
      A = pi*(.21)^2;
      C = .12;
      p0 = 1.225;
      g = 9.81;
      %Initial Conditions
      dt = .001;
      x(1) = 0;
      y(1) = 0;
      v = 10000;
      angle = 20;
      vx = v*cosd(angle)
      vy = v*sind(angle);
      t(1) = 0 ;
      i = 1;
      y0 = 1000;
      while min(y)> -.001
      p = p0*exp(-y/y0)
      Drag = p*C*A/2*v^2
      ax = -(Drag/m)*(vx*vx+vy*vy)^0.5*vx;
      ay = -g-(Drag/m)*(vx*vx+vy*vy)^0.5*vy;
      vx = vx+ax*dt;
      vy = vy+ay*dt;
      x(i+1) = x(i)+vx*dt+.5*ax*dt^2;
      y(i+1) = y(i)+vy*dt+.5*ay*dt^2;
      t(i+1) = t(i)+dt;
      i = i+1;
      end
      plot(x,y,'-')
      xlabel('x distance (m)')
      ylabel('y distance (m)')
      pause(0.001);


      I cannot get the correct simulation here. If I take drag as constant and place it in initial conditions, it works fine. But when I put it in the while loop, the whole simulation gives me absolute nonsense. I would appreciate your help.







      matlab projectile






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      edited Jan 1 at 8:25









      Sardar Usama

      15.4k82548




      15.4k82548










      asked Dec 30 '18 at 14:18









      OzanTOzanT

      11




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