MCAT Physics Question — Pressure
 by
 Dec 31, 2014
 MCAT Blog, MCAT Physics, MCAT Question of the Day
At a depth of 5 meters, the pressure in a tank of water is equal to 1.5 atm. What is the pressure at a depth of 20 meters?
A) 3 atm
B) 4 atm
C) 5 atm
D) 6 atm
Explanation
This question is testing your understanding of the relationship between total pressure, atmospheric pressure, and gauge pressure: P_{total }= P_{atm }+ P_{gauge}. To begin, you must know that P_{atm }results from the pressure of the atmosphere and P_{gauge} results from the pressure due to the fluid. To calculate the gauge pressure, you can use the equation P_{gauge }= rgd, where r is the density of the fluid, g is gravity, and d is the depth below the surface of the fluid.
At a depth of 5 meters, P_{gauge }= rgd = (1000 kg/m^{3})(10 m/s^{2})(5 m) = 50,000 N/m^{2} or ~0.5 atm. Therefore, the P_{atm }is equal to 1 atm. Thus, at a depth of 20 m, P_{total }= P_{atm }+ P_{gauge} = 1 atm+ (1000 kg/m^{3})(10 m/s^{2})(20 m) = 3 atm, making A the correct answer.
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 Advisor using the form below. No obligation, just expert advice.
Search the Blog
Free Consultation
Interested in our Online MCAT Course or one of our OneonOne MCAT Tutoring packages? Set up a free consultation with one of our experienced Academic Managers!
Schedule NowPopular Posts

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