Key formula:

L = I x omega = moment of inertia x angular velocity

I = 0.4 x r^{2} x M #(for a sphere)

In [17]:

```
r = 6378000 # meters
M = 5.97E24 # kg
```

omega = 2 x pi radians per day

But what is that in radians per second?

In [18]:

```
omega = (2 * pi) / (60*60*24)
print omega
```

In [19]:

```
I = 0.4 * r**2 * M
print I # unit is m**2 * kg
```

In [20]:

```
L = I * omega
print L # unit is m**2 * kg * rad/s
```

Note that 1 joule = 1 kg x (m^{2}/s^{2})

Interesting side note: The answer above means you'd apply 7 x 10^{33} joules of energy to the earth over the course of 1 second... this implies that the power you'd need is 7 x 10^{33} watts, or about 7 trillion trillion trillion megawatts. If you wanted to know whether your car engine could do it, you'd need to call the manufacturer and ask if your V8 can be souped up to have 936 thousand billion billion billion brake horsepower.

If you had all day to end the world as we know it instead of just 1 second, you'd only need about a hundred and ten billion billion billion brake hp as we can see by changing a few variables: (smallpaul ran out of energy here...but you can imagine it)

In [21]:

```
# change some variables and redo it.
```

In []:

```
```