# Help me understand the meaning of these lines

• B
Gold Member

## Main Question or Discussion Point

What does the author want to say through these lines?
What is the *harm* he is talking about?

I will be thankful for any help!

#### Attachments

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It's a strange way to describe things. The calculation involving a finite $dx$ is an approximation. You effectively take the mass element from $x$ to $x + dx$ all to be at position $x$. As $dx$ gets smaller, the approximation gets better. The limit $dx \rightarrow 0$ is the integral.