He thought that some dreadful shock had turned her brain.

他认为是某种可怕的震惊改变了她的大脑。

And, when she stops suddenly, velocity decreases rapidly back to zero miles per hour, her brain would crash into the other side of her skull, turning her brain into mush.

而当她突然停下来，速率快速回归於零，她的大脑会撞到另一边头骨边缘，把大脑变成一团糊。