Q$3.$ A four$-$stroke four$-$cylinder spark$-$ignition engine having a bore of $100$ mm and stroke of $120$ mm and running at $3000$ rpm has a carburetor venturi with a $35$ mm throat diameter. The volumetric efficiency of the engine at this speed is $80\%,$ the coefficient of discharge of air flow is $0\mathrm{.}82.$ The ambient pressure and temperature are $1\mathrm{.}013$ bar and $25C$ respectively. The air fuel ratio is $15.$ The top of the jet is $5$ mm above the petrol level in the float chamber. The coefficient of discharge for fuel flow is $0\mathrm{.}7.$ Determine the depression at the throat and the diameter of fuel jet of a simple carburettor. $($The specific gravity of petrol is $0\mathrm{.}75).$

$($Ans: p$1-$p$2=0\mathrm{.}05407$ bar, $dj=1\mathrm{.}95mm)$