Return to MCAT® Blog Homepage

MCAT Physics Question — Pressure

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: Ptotal = Patm + Pgauge. To begin, you must know that Patm results from the pressure of the atmosphere and Pgauge results from the pressure due to the fluid. To calculate the gauge pressure, you can use the equation Pgauge = 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, Pgauge = rgd = (1000 kg/m3)(10 m/s2)(5 m) = 50,000 N/m2 or ~0.5 atm. Therefore, the Patm is equal to 1 atm. Thus, at a depth of 20 m, Ptotal = Patm + Pgauge = 1 atm+ (1000 kg/m3)(10 m/s2)(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 full-length 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.

Schedule My Free Consultation

MCAT is a registered trademark of the Association of American Medical Colleges (AAMC), which is not affiliated with Blueprint.