MCAT Physics Question — Pressure Difference
 by
 Jul 21, 2017
 MCAT Question of the Day
If the pressure difference measured at two depths of a tank of mercury is 130,000 Pa, what is the height difference between the two depths? (Use specific gravity of mercury = 13 and gravity = 10m/sec^{2})
A. 10cm
B. 1m
C. 10m
D. 1000m
Click for Explanation
In a column of fluid, the pressure difference between two depths is given by the formula ΔP = (SG)ρ_{water}gh, where ΔP is the pressure difference, SG is the specific gravity of the fluid, and ρ_{water}gh is the product of water density, gravity, and height difference. Remember that specific gravity, SG, is the ratio of fluid density to water density. Water density is 1g/cm^{3} or 1000kg/m^{3}.
130,000Pa = 13* 1,000kg/m^{3} * 10 m/sec^{2 }* h, h = 1m.
A. 10cm, incorrect.
B. 1m, correct.
C. 10m, incorrect, This answer neglects the contribution from gravity.
D. 1000m, incorrect, This answer uses 1kg/m^{3} for the density of water rather than the correct value of 1000kg/m^{3}.
Want more MCAT practice?
We’ve got options for every schedule and learning style!
From the best online MCAT course created by top instructors with 524+ MCAT scores to the most representative fulllength practice exams and private tutoring, we can custom tailor your MCAT prep to your goals!
Not sure which option is right for you? Schedule a free MCAT consultation with an MCAT expert using the form below. No obligation, just expert advice.
Search the Blog
Free Consultation
Interested in our Online MCAT Course, OneonOne MCAT Tutoring or Med admissions packages? Set up a free consultation with one of our experienced Senior Student Advisors.
Schedule NowPopular Posts

MCAT Blog What's on the MCAT?

MCAT Blog How to Review MCAT FullLengths
Free MCAT Practice Account
Need great MCAT practice?Get the most representative MCAT practice possible when you sign up for our free MCAT Account, which includes a halflength diagnostic exam and one of our fulllength MCAT practice exams.
Learn More
Submit a Comment