Okay, also dann...

... switch schon jetzt wieder um.

Ja?

So.

Last time we discussed...

... further...

... the different balance equations.

So,

...

... last time we discussed...

... further...

... the different balance equations.

So,

... last time we discussed...

... the different balance equations...

... or balance laws...

... that are of relevance here.

...

Number one was the mass...

... conservation.

And number two here is...

... linear momentum.

This is just again the...

... definition of linear momentum.

Mass density...

... times velocity instead of...

... mass times velocity...

... that we had for the...

... mass points.

Then the integral over the whole body...

... renders the total linear momentum...

... or the integral over the...

... let's say...

... control volume here.

And then the balance of...

... linear momentum is simply...

... Newton's law.

So the change in linear momentum is...

... due to the forces.

The forces split into two terms.

These are the body forces...

... and the tractions that are...

... acting at the surface...

... of the body.

And if you then transform...

... this...

... surface integral by the help...

... of the Cauchy theorem...

... that we are going to discuss...

... in a minute in more detail...