system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] If Flash stands on a manhole cover that's then blasted into the air by an explosion, would he be damaged, or unharmed because his body is accustomed to those kinds of forces?
gpt
Speedforce only grants Flash immunity to forces he (well, it) causes. That's why he isn't damaged by an Infinite Mass Punch, but you can knock him out with a Regular Left Cross.

However, Flash's reaction times are fast enough that he could recognize the explosion and get away from it before it overtook him. He could also (probably) speed-steal from the explosion itself, nullifying it.