how to create a vector

Hello everyone, I hope you are doing well. I need some help with my matlab project. I''m finding the velocity and time after each 1 meter displacement. It''s good when I''m doing that and I''m actually getting correct results. However, I couldn''t find the velocity and time after for example 1.5 or 1.6 meter. this is my program, so can you please help me with it.

function [v,t]=freefall(h)  
g=9.81;
%Gravity in m^2/s 
for k=1:h
    v(k)=sqrt(2*g*k);
end 
for
k=1:h
    t(k)=sqrt(2*k/g);
end 

plot(t,v)
xlabel(''Time
(s)'')
ylabel(''Velocity (m/s)'')
title(''Free fall: velocity vs time'')

Answer 1

[Star Strider]

Use the interp1 function.

If I understand your code correctly, this will work. Add these lines to the end of your code:

k = 1:h;                                                    % Displacement
dspl_intrp = [1.5; 1.6];                                    % Displacements To Interpolate
vt_intrp = interp1(k, [v' t'], [1.5; 1.6], 'linear');       % Interpolate Velocity & Time
fprintf(1, 'Displacement %.2f,  Velocity = %.2f,  Time = %.2f\n',  [dspl_intrp vt_intrp]')

Displacement 1.50,  Velocity = 5.35,  Time = 0.55
Displacement 1.60,  Velocity = 5.53,  Time = 0.56

I added the fprintf call to show that the result appears to be correct.

[Abdullah Jizani]

I think you misunderstood my question. I'm asking for how to get a result for each 0.1 m.

[Star Strider]

That’s even easier.

Set:

k = 1 : 0.1 : h;

[Abdullah Jizani]

but it shows me this error ??? Attempted to access v(1.1); index must be a positive integer or logical.

Error in ==> freefall at 7 v(k)=sqrt(2*g*k);

[Star Strider]

I forgot that you used it as an index.

This works:

g=9.81; %Gravity in m^2/s 

d = 1 : 0.1 : h;                                    % Displacement Vector
for k=1:length(d)
    v(k)=sqrt(2*g*d(k));
end 
for k=1:length(d)
    t(k)=sqrt(2*d(k)/g);
end 

plot(t,v)
xlabel('Time (s)')
ylabel('Velocity (m/s)')
title('Free fall: velocity vs time')

Note that here you have to change the ‘k’ reference as the independent variable in your calculations to ‘d(k)’. This also gives you flexibility to make ‘d’ anything you want, even negative or zero, because ‘k’ is now derived from it.