What is the change in density of water at a depth of 400 m?

AI Thread Summary
To determine the change in density of water at a depth of 400 m, the initial density is given as 1030 kg/m³ and the bulk modulus is 2 x 10⁹ N/m². The relevant equation for new density involves the change in pressure (dP) and the bulk modulus (B). There is uncertainty about whether to use the surface density for calculating dP or if integration is necessary due to varying density with depth. The pressure can be calculated using the formula P = h × surface density × g. Understanding these calculations is crucial for accurately determining the density change at that depth.
Abhishekdas
Messages
198
Reaction score
0
Bulk modulus question...please help

Homework Statement


What is the change in density of water in a lake at a depth of 400 m below the surface? The density of water at the surface is 1030 kg/m3 and bulk modulus of water is 2*109 Nm2


Homework Equations


For fluid
New Density= Initial density*(1/1-dP/B)
dP=change in pressure and B=bulk modulus


The Attempt at a Solution



My doubt is can we apply dp=h*density*g here taking the initial density (1030) because density is not constant throughout...Do we have to integrate or something...? What do do?
 
Physics news on Phys.org


ANy replies here...please...
 


Abhishekdas said:
ANy replies here...please...

You can take P = h X surface density X g
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top