Gauge Pressure at the Bottom of Ocean on Mars

  • #1
forestmine
203
0

Homework Statement



Scientists have found evidence that Mars may once have had an ocean .5km deep. The acceleration due to gravity on Mars is 3.71m/s^2.

(a) What would be the gauge pressure at the bottom of such an ocean, assuming it was freshwater?
(b) To what depth would you need to go in the Earth's ocean to experience the same gauge pressure?

Homework Equations



p=p[itex]_{0}[/itex]+ρgh

gauge pressure = absolute pressure - atmospheric pressure

The Attempt at a Solution



What I'm thinking is that I can calculate the absolute pressure by using p=ρgh, so p=(1000)(3.71)(500)=1855000 Pa.

But I think I'm getting a little confused about my absolute and atmospheric pressures. Absolute should be the pressure at the bottom of 500m, I believe. What should I be using for my atmospheric pressure?
 

Answers and Replies

  • #2
rock.freak667
Homework Helper
6,223
31

Homework Equations



p=p[itex]_{0}[/itex]+ρgh

gauge pressure = absolute pressure - atmospheric pressure

if P = absolute pressure, then P-P0 would be the gauge pressure wouldn't it? (or just 'ρgh'.

The Attempt at a Solution



What I'm thinking is that I can calculate the absolute pressure by using p=ρgh, so p=(1000)(3.71)(500)=1855000 Pa.

But I think I'm getting a little confused about my absolute and atmospheric pressures. Absolute should be the pressure at the bottom of 500m, I believe. What should I be using for my atmospheric pressure?
 
  • #3
forestmine
203
0
Ok, so you're saying I've already calculated the gauge pressure by neglecting p[itex]_{0}[/itex] in my earlier equation?

If that's the case, how would I go about solving part b?
 
  • #4
BetoG93
34
0
I am pretty sure that gauge pressure doesn't involve atmospheric pressure. Since Mars' atmosphere is quite different to Earth's, atmospheric pressure there has a value different than 101 kPa.
Anyway, the only equation you need is P = pgh (p is density; my cell phone doesn't have rho).
 
  • #5
rock.freak667
Homework Helper
6,223
31
Ok, so you're saying I've already calculated the gauge pressure by neglecting p[itex]_{0}[/itex] in my earlier equation?

If that's the case, how would I go about solving part b?

Right, well you'd use the gauge pressure you got earlier and using the same formula just with Earth values i.e. the value of 'g' on Earth.
 

Suggested for: Gauge Pressure at the Bottom of Ocean on Mars

Replies
3
Views
145
Replies
38
Views
675
Replies
5
Views
512
Replies
22
Views
660
Replies
7
Views
439
  • Last Post
Replies
2
Views
1K
Replies
5
Views
1K
Top