As the engineer on the job, you are tasked to determine the pressure drop across an orifice (an obstruction with an opening) placed in a channel where g = 9.81 m/s². Initially, there is air flowing in this channel from left to right. The pressure measurement is done with a mercury manometer with a constant cross-sectional area, showing a height difference of 200 mm. Density of Mercury is 13,600 kg/m³ a) Calculate the pressure drop across the orifice (p1-p2) between the two holes flush with the bottom of the channel in kPa. Density of air is p≈ 1.225 kg/m³. Determine if you could have ignored the unequal air columns. Yes? No? Why? b) Later, instead of air, liquid water (p = 1000 kg/m³) flows through the channel. Recalculate the pressure difference across the orifice. Determine if you could have ignored the unequal water columns. Yes? No? Why? Hint: Set up a force balance at the very bottom of the manometer. P₁ HIGHC U Н P₂ m₂