Projectile Motion 2D plot without drag

Question

MG 2015-11-8

0
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https://ww2.mathworks.cn/matlabcentral/answers/253791-projectile-motion-2d-plot-without-drag

评论： MG 2015-11-9

Hi all. I am plotting a 2D plot of projectile motion, where speed and height are on the y axis and time is on the x axis. My speed is wrong, however. The speed is correct when plotted by itself, but when plotted with height, the graph seems to shift to the left. The point at which speed is supposed to be 0 is at t = 3.0581 s, which is what happens when I plot it on its own. But in the plot below its at 2.7 or 2.8 seconds. How do I fix this? I'm pretty sure there's something wrong with my 2D plot specification but I'm not sure what.

function [v, h] = projectile (v_0, theta, diagram)
% Gravitational acceleration, in m/s^2
g = 9.81;
% Time taken to hit the ground, s
t_hit = 2*(v_0/g)*sind(theta);
% Overall time taken from launch to hitting ground, s
t = 0:0.005:t_hit;
% Height, m
h = v_0*t*sind(theta)-(1/2)*g*(t.^2);
% Speed, m/s
v = sqrt(((v_0)^2)-(2*v_0*g*t*sind(theta))+(g^2)*(t.^2));
      % Optional plotting; diagram = 1 is a true condition so v, h and plots
      % will be outputted, otherwise diagram = 0 is a false condition and 
      % only v and h are outputted
      if diagram == 1;
          [ax,p1,p2] = plotyy(t,h,t,v);
          set(p1,'linewidth',1.5);
          set(p2,'linewidth',1.5);
          % Label x-axis
          xlabel(ax(1),'Time (s)')
          % Label left y-axis
          ylabel(ax(1),'Height (m)')
          % Label right y-axis
          ylabel(ax(2),'Speed (m/s)')
          % Set limits for x-axis
          set(ax(1),'XLim',[0 6.1162]);
          set(ax(1),'XTick',[0:1:6.1162]);
          % Set limits for left y-axis
          set(ax(1),'YLim',[0 45.8550]);
          set(ax(1),'YTick',[0:20:45.8550]);
          % Set limits for right y-axis
          set(ax(2),'YLim',[0 30]);
          set(ax(2),'YTick',[0:10:30]);
          % Vertical grid lines only
          set(gca,'XGrid','on')
          set(gca,'YGrid','off')
      else
          diagram = 0;
      end
  end