# What is this integration?

This is from the book introduction to mechanics by Kleppner D. Is it some typo, or something i don’t understand? Does F dt comes down in front of integration?

• Definitely a "bug" in the book typesetting. – John Alexiou Jul 31 at 12:06

$$\underbrace{\int F dt}_{1\text{ collision}}$$
• the "1 collision" just looks like description of integral bounds, so I think it should be $\int_\text{1 collision} F dt$. – Umaxo Jul 31 at 5:42