A fat hose pipe is held horizontal by a fireman. It delivers water through a constricting nozzle at i liters/ sec. It by increasing the pressure the water is delivered at 2 liter/sec. the fireman now has to
a. push forward twice as hard
b. push forward four times as hard
c. push forward eight times as hard
d. pull backward four times as hard

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2 Answers
Lokesh Verma
·20081108 21:38:42
umm.. bcos u havent posted it yet...
so i guess u havent got my hint..
try F=d(mv)/dt
F=dm/dt.v+m.dv/dt
for both the cases use this..
but yeah dv/dt will be 0? (why??)
and dm/dt will be in terms of A(area of cross seciton) and velocity (why and what)
Now companere this expression of F for both these cases.. u will get the answer :)