Question

In a manometer, if the atmospheric pressure pushes the mercury down, you should (add/subtract) the pressure difference.

A) Add
B) Subtract

Answer 1

In an open-end manometer, you should add the pressure difference if the atmospheric pressure pushes the mercury down. In a closed-end manometer, the gas pressure is equal to the difference in the height of mercury in the two arms of the U-tube.

Step-by-step explanation:

In an open-end manometer, if the atmospheric pressure pushes the mercury down, you should add the pressure difference.

In a closed-end manometer, the gas pressure is equal to the difference in the height of mercury in the two arms of the U-tube.

So, to calculate the pressure difference in an open-end manometer, you need to add the atmospheric pressure to the difference in the heights of the two columns of mercury.