Multiple projectile plots

Hi, I'm trying to plot multiple projectiles on a graph. The projectiles at launched between 60 and 80 degrees with a one degree increment.

The launch velocity is specified by the Lanunch angle, to ensure it reaches the desired coordinates (6.7,3.05).

So the (x,y)graph I wanted would show 21 different trajectories.

However when I put my code in, Matblab only plots one line and I'm not really sure what it represents.

My code is:

%Angles of Projectile theta=[60:1:80];

%Launch velocity from given theta u=((((9.81/2)*1.25.^2)*(1+(tand(theta)).^2)./((1.25*tand(theta))-0.55))').^(0.5);

%Horizontal positions x=[0:0.335:6.7];

%Vertical Positions y=(x*tand(theta)')-((9.81/2)*(x.^2))./(((u.^2).*(cosd(theta))'.^2)')+2.5;

%Graph of projectiles plot(x,y)

Can anyone point out my error or what I should do? Thanks.

Answer 1

[Thomas]

My understanding is that you change the theta and the x values..

declare theta and x

for change in theta
for change in x
compute u   % remember to get  u as vector u(i) or u(j) 
compute y   % remember to get  y as vector y(i) or y(j) 
end  % to compute at this theta and all values of x giving you   
      %one set of values of y
plot(x,y)  % to plot the first curve
hold on % to show more curves on same graph
end    % to go to next value of theta and repeat

[Stuart]

Thanks Thomas,

I'm not really sure how I should add this into my code.

Should I enter u(i) and y(i)?

[Thomas]

Think about how you get a vector for y?

You can svae the output in a vector or matrix as shown,

Eg:

for i=1:10

y(i)=i+rand; % us y(i) so that it is written as a vector

end

or you could use:

z=[];

for i=1:10

z=[z i+rand];

end

both should give you similar results..