TBR physics question on section 7

[Nasem]

Example 7.2b is pissing me off...

I can't figure out how the hell the answer is C (I know its either C or D, but why C, hows the math working here)

Can someone explain plz?

A swimmer is at the bottom of a 5-meter pool, where the gauge pressure (pgh) is approximaterly 0.5 Patm. If the swimmer rises to the surface, by how much does the total pressure change?

A) the total pressure increases by 33%
B) the total pressure increases by 66%
C) the total pressure decreases by 33%
D) the total pressure decreases by 66%

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[NeuroChaos]

I think u missed the TOTAL Pressure.

u r told that the guage pressure is .5 atm ....which means total pressure = 1.5 atm

if he comes up what is the guage pressure 0 atm...but what is the total pressure = 1

change in pressure = .5

another key: by how much does the TOTAL pressure CHANGE

now take the ratio = .5/1.5 = 33%

hope that helped

 

[Nasem]

Ok, so I should have assumed this was on sea level, where the Air pressure is 1 atm and adding to it the underwater pressure (given in the problem = 0.5 atm)

So what your saying makes PERFECT sense, thank you

I just didn't realise to add the 1 atm sea level pressure, I figured since its not given, I shouldn't think along those lines lol (silly me)