how to Calculate Gravity

A Spherical Cavity Of Radius 8 M Has Its Center 15 M Below The Surface. If The Cavity Is Full Of Water And The Surrounding Rock Has A Density Of 2400kg/M3. Calculate The Gravity Anomaly along the surface with a spacing of 5m

write a matlab script to calculate this anomaly and represents it graphically

clear all
close all
clc
r=8;
z=15;
x=0:10:100;
dp=2400;
G=6.67e-11;
for i=1:100;
    g(i)=(G*4*pi*(r^3)*z)/(x^2+z^2)^(3/2);
    
end

Error using ^
Incorrect dimensions for raising a matrix to a power. Check that the matrix is square and the power is a scalar. To operate on each element of the matrix individually, use POWER (.^) for elementwise power.

plot(x,g(i))

could you help me figur out the mistake?

Answer 1

[the cyclist]

You are not indexing into x correctly. Here is one way to fix it:

r=8;
z=15;
x=0:10:100;
dp=2400;
G=6.67e-11;
for i=1:numel(x)
    g(i)=(G*4*pi*(r^3)*z)/(x(i)^2+z^2)^(3/2);
end

plot(x,g) % I fixed this, too. Plot the whole vector of g

You don't need the for loop, though:

r=8;
z=15;
x=0:10:100;
dp=2400;
G=6.67e-11;
g=(G*4*pi*(r^3)*z)./(x.^2+z^2).^(3/2);

plot(x,g)

[Abubakr Mursi]

thanks deeply

[Dyuman Joshi]

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