presure- units

[evusq]

i'm used to using atm, and exam kracker seems to put an emphasis on using pascal, so i'm a bit thrown off.. can someone please confirm/correct me?

1. in ideal gas law, PV=nRT, use atm
2. in bernoulli's equation, P+ pgh, covert pressure to pascal?? (this is what exam kracker tells me.. but i wasn't sure)
3. when you do pressure vs work digram, and calculate W=-p*deltaV, should you use the pressure in pascal??

thanks!!

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[wooki]

i'm used to using atm, and exam kracker seems to put an emphasis on using pascal, so i'm a bit thrown off.. can someone please confirm/correct me?

1. in ideal gas law, PV=nRT, use atm
2. in bernoulli's equation, P+ pgh, covert pressure to pascal?? (this is what exam kracker tells me.. but i wasn't sure)
3. when you do pressure vs work digram, and calculate W=-p*deltaV, should you use the pressure in pascal??

thanks!!

for all 3 you can kind of really use differing units of pressure: atm, kPa, Pa, mmHg, etc. you just have to look at the units of the other variables they give you. for example, for 1, the only reason you are using atm most of the time is because you use R = .082, n -> moles, T -> kelvins. but yes most of the time pressure is atm, unless the question says otherwise.

so don't try to memorize which unit of pressure to use with each, instead just know the conversion rates for pressure.
1 atm = 760 mmHg = 760 torr = 101kpA

 

[BerkReviewTeach]

for all 3 you can kind of really use differing units of pressure: atm, kPa, Pa, mmHg, etc. you just have to look at the units of the other variables they give you. for example, for 1, the only reason you are using atm most of the time is because you use R = .082, n -> moles, T -> kelvins. but yes most of the time pressure is atm, unless the question says otherwise.

so don't try to memorize which unit of pressure to use with each, instead just know the conversion rates for pressure.
1 atm = 760 mmHg = 760 torr = 101kpA

Well put! Use the units the question presents or the constant uses.