Problem with Pressure Equation units

In summary, the conversation discusses the confusion over the units for pressure in the equation P=P(STP)+ρgd. After working it out, it is determined that the units of ρgd (kg/m-s2) do indeed equal 1 Pascal. The explanation given is that 1 Pascal is equivalent to 1 kg/m-s2.
  • #1
SanEng02
5
0
I was doing a problem that required me to initially find the amount of pressure that was acting on a bubble, I decided that I had to use the equation P=P(STP) + ρgd. But looking at the equation, the units for the ρgd part of the problem doesn't make sense about how that gives me a unit of pressure (Pascal).2. So I worked it out and:

ρ= kg/m^3
g= m/s^2
d= m

when multiplied together your units become kg/ms^2 which you are then adding to a pascal unit. So my question really is, is 1 kg/ms^2 = 1 Pa?

An explanation would be much appreciated!
 
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  • #2
SanEng02 said:
I was doing a problem that required me to initially find the amount of pressure that was acting on a bubble, I decided that I had to use the equation P=P(STP) + ρgd. But looking at the equation, the units for the ρgd part of the problem doesn't make sense about how that gives me a unit of pressure (Pascal).2. So I worked it out and:

ρ= kg/m^3
g= m/s^2
d= m

when multiplied together your units become kg/ms^2 which you are then adding to a pascal unit. So my question really is, is 1 kg/ms^2 = 1 Pa?

An explanation would be much appreciated!

1 Pascal = 1 Newton / m2

1 Newton = 1 kg-m/s2 [Using F = m a]

Therefore, 1 Pascal = 1 N / m2 = 1 kg m/s2 × (1/m2) = 1 kg / m-s2

Compare with the units arising from the product ρgd. :wink:
 
  • #3
Thank you so much! Makes sense now!
 

1. What is the problem with pressure equation units?

The problem with pressure equation units is that there are multiple units used to measure pressure, such as pascals, atmospheres, and psi. This can lead to confusion and incorrect calculations if the units are not converted properly.

2. Why is it important to use consistent units in pressure equations?

Using consistent units in pressure equations is important because pressure is a measure of force per unit area. If different units are used for the force and area components of the equation, the resulting pressure value will be inaccurate.

3. How can I convert between different pressure units?

To convert between different pressure units, you can use conversion factors. These conversion factors can be found in unit conversion tables or can be calculated using the relationships between the units. It is important to carefully track the units and make sure they cancel out correctly in the conversion process.

4. What is the most commonly used unit for pressure in scientific calculations?

The most commonly used unit for pressure in scientific calculations is the pascal (Pa). This is the SI unit for pressure and is defined as one newton of force per square meter. Other commonly used units include atmospheres, which is often used in meteorology, and psi, which is commonly used in engineering.

5. How can I avoid errors in pressure equations due to unit conversion?

To avoid errors in pressure equations due to unit conversion, it is important to double check all units used in the equation and make sure they are consistent. It can also be helpful to convert all units to the same system, such as SI units, before performing calculations. Additionally, using a calculator or spreadsheet with built-in unit conversion functions can help minimize errors.

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