Question

Why a fire man hold hose pipe tightly

Answer 1

the water coming out from the pipe exerts a force on the fire man . to counter this force the fire man applies a muscular force from his side to nullify the reaction force of the hose and thus he remains on his place.

(or else he would fly somewhere...XD)

Answer 2

Answer:

because the water is coming out of the pipe with a great force and hence to control the heavy force of water , he has to hold the pipe very tightly

hope this helps you