# Homework Help: Plotting tidal force vectors on the surface of the earth

1. Apr 27, 2013

### Dustinsfl

How can I plot the tidal force vectors on the surface the Earth in Mathematica or Python?

The potential energy of the tidal force on the poles are
$$U = -GM_{moon}m_{water}\left(\frac{1}{d}+\frac{x}{d_0^2}\right)$$
where $d_0$ is the distance between the moon and the earth 384400 km.

The equation of motion for forces acting on mass m is
$$m\ddot{\mathbf{r}} = m\mathbf{g} + \mathbf{F}_{NG} - GM_{moon}m_{water}\left(\frac{\hat{\mathbf{d}}}{d^2} - \frac{\hat{\mathbf{d}}_0}{d_0^2}\right)$$

Force ng is the non gravitational forces.

I am not sure what I need to use to plot the vector lines coming from the Earth due to the moon.

I know the tidal forces bulges out on the horizontal ends and pushes in on the poles.

2. Apr 27, 2013

### Staff: Mentor

this might help for plotting on a sphere using matlab:

You just have to modify the code for what you want. There may be another addition that will draw an earth profile on the sphere but I couldn't find it.

3. Apr 28, 2013

### Dustinsfl

4. Apr 28, 2013