The effect of hand fans for better breathing in emergencies Suppose I am in a room or system with a lot of smoke and it is difficult to breathe. If I put a hand fan in front of my face, does the wind from the fan blow the smoke away from my face, making it easier for me to breathe, or does it increase the intensity of the smoke and make it harder for me to breathe? How can this phenomenon be explained in terms of physics?

I think that if the room is full of smoke, then it will get more difficult to breathe

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me