$2)$ Consider a U$-$tube whose arms are open to the

atmosphere. Now equal volumes of water $(\backslash$rho $=1000$ kg$/$m$3$

$)$

and light oil $(\backslash$rho $=789\mathrm{.}7$ kg$/$m$3$

$)$ are poured from different

arms. A person blows from the oil side of the U$-$tube until

the contact surface of the two fluids moves to the bottom

of the U$-$tube, and thus the liquid levels in the two arms

are the same. If the fluid height in each arm is $76$ cm$,$

determine the gage pressure the person exerts on the oil

by blowing