3.1. Calculating Pressure Difference between Points M and N

Try these first

1. 1.

   What is a differential manometer used for?

   Hint

   Think about what we need to know about the fluid in the system.

2. 2.

   What do you calculate first when measuring pressure with a manometer?

   Hint

   Consider where you need to begin for calculations.

3. 3.

   What does the specific gravity tell you about a fluid?

   • Weight of the fluid only
   • Density relative to water
   • Viscosity of the fluid

   Hint

   Think about how densities compare.

4. 4.

   True or False: The pressure at point N can be greater than at point M if the calculated difference is negative.

   • True
   • False

   Hint

   Reflect on the calculations.

5. 5.

   Two tanks contain the same height of liquid A (specific gravity 0.85) 2 m high in one tank and liquid B (specific gravity 0.92) 3 m in the other. What is the pressure difference at the bottom of both tanks?

   Hint

   Don't forget to compare the results once calculated.

6. 6.

   A manometer reads oil (SG=0.82) above water (2 m of oil and 4 m of water). Calculate the pressure difference and classify if it is a positive or negative difference.

   Hint

   Check if the values indicate a higher oil pressure or lower water pressure!