It's not a trick, not a joke, and not a vector problem.
The formula F = MA is correct.
Irregardless of Mass ... given zero Acceleration the force is zero.
It might be interesting to try the question out on whiz kids you know.
That sounds fishy to me. So if I’m bench pressing and I get stuck half way up, I’m not exerting force? I understand the math aspect, since zero times anything is zero. If my force is zero, what am I exerting?
Yes. And zero=zero. No ± sign, no sine...
Yes. And zero=zero. No ± sign, no sine, no sighin’...
That’s not true. There’s still a force that you are exerting on the doorframe, it’s just not strong enough to overcome any counteracting forces, to create an acceleration in the doorframe. You’re still exerting a force though.