1. ### Does this wave propagation problem make physical sense?

Hi, I'm trying to make sense of a wave propagation problem. It's a 1D problem, modelling propagation of density perturbations which travel like waves in a fluid. The problem is governed by the mass and momentum equations and density is related to pressure using the bulk modulus of the fluid...
2. ### Floating Cylinder of Uniform Density

A solid cylinder of uniform density of 0.85 g/cm3 floats in a glass of water tinted light blue by food coloring...
3. ### Density of bar submerged in water

Homework Statement A bar suspended in air weighs 1.75 N The same bar weigs only 1.4 N when suspended in water. Calculate; a. upthrust b. density of the bar Homework Equations D = m/v F = m*a The Attempt at a Solution a[/B]. Upthrust is 1.75 N - 1.4 N = 0.35 N b. Assuming density of water...
4. ### Change of g due to oil deposit

Homework Statement The center of a 1.00 km diameter spherical pocket of oil is 1.00 km beneath the Earth's surface. Estimate by what percentage g directly above the pocket of oil would differ from the expected value of g for a uniform Earth? Assume the density of oil is 8.0*10^2 (800) kg/m^3...
5. ### Light if energy density of photons were constant

Homework Statement At what rate would stars have to be producing light (how many photons per second per solar mass start) in order for the energy density of photons in the universe be constant? Assume current values of cosmological parameters. Do it for current time. Homework Equations e =...
6. ### Hubble lookback time based on energy density.

Homework Statement If the energy density of the vacuum were the value 10^133 eV/m^3 , what would the value of the Hubble lookback time be for such a universe with no curvature and no other matter? Homework Equations Possible equation... ...Lookback time = ln(1+z)/H The Attempt at a Solution...
7. ### Mass of one component in two component w/feed flowrate

Homework Statement Basically I'm given a feed flowrate - 70,000 gal/day I know the weight percent is 35% and the component is Triethylene Glycol - density - 1.255g/ml Homework Equations The Attempt at a Solution So i did this 70,000 gal/day * .35 * (.0378mL/1gal)* 1.255g/mL = g of...
8. ### Conditional PDF question -- I think anyway...

Homework Statement Suppose you take a pass-fail test repeatedly. Let Sk be the event that you are successful in your kth try, and Fk be the event that you fail the test in your kth try. On your first try, you have a 50% chance of passing the test. P(S1)=1−P(F1)=1/2. Assume that as you take the...
9. ### Rotating water container

Hi, I was recently thinking about a problem which I have no idea how to solve. A full water container with volume V is hanged on a rope with length L (mass of the rope is negligible). It then starts to revolute around the point where the rope is hooked (circular motion, circle with radius L)...
10. ### Experimental Error in Archimedes Principle Lab

Homework Statement I need to find three potential reasons for my .5% error in a lab where I used the Archimedes Principle to measure the density of Iron. We only used a graduated cylinder full of water and an iron mass. I measured the water level from the meniscus. We used two different...
11. ### Second Quantization Density Matrix

Homework Statement Homework Equations and attempt at solution I think I got the ground state, which can be expressed as |\Psi \rangle = \prod_{k}^{N}\hat{a}_{k}^{\dagger} |0 \rangle . Then for the density matrix I used: \langle...
12. ### Force needed to pull something from something liquid

Hi... any idea on how to calculate force needed to pull up something stuck on the ground? ex: Boot stuck on mud person sinking on quicksand or car sinking in water
13. ### Calculating sand penetration of ice solid from height X

G’day physics forum This is a purely hypothetical question and my knowledge of physics is rather limited so I’ve no idea if answering it is even possible however here goes: Imagine a 30cm long timber stick approximately 3mm in diameter that has been placed vertically in an inverted pyramid or...
14. ### What causes the liquid to rise in this picture?

This is a diagram of a pitot-static tube. My question is however not related to its applications but rather, what causes the liquid to rise up the static tube? The static tube is at right angles to the fluid flow. I understand that this is a very basic question but I can't seem to get my head...
15. ### Does local realism imply separability?

Hi. Bell's formulation of local realism is $$P(a,b)=\int\ d\lambda\cdot\rho(\lambda)p_A(a,\lambda)p_B(b,\lambda)\enspace.$$ Let's for simplicity assume there's only a finite number of states, so this becomes $$P(a,b)=\sum_{i} p_i\cdot\ p_A(a,i)p_B(b,i)\enspace.$$ I'm trying to translate this...
16. ### Why Does Density Affect the Density of its Container?

I've never been able to figure this out. I can understand when you put oil in water that one floats on top of the other, but why does it still work if I put it into a balloon? Something that keeps it from directly interacting with the medium it's in?
17. ### Density of Solution and mass percent

There are two numericals, 1. Density of Methanol is 0.793 kg/l. Find molarity. ANSWER is : Desity/ Molar mass = Molarity (UNDERSTANDABLE) In other numerical 2. Concentration of H2SO4 is 98% by mass having density of 1.84gm/ml. Calculate Molarity. here they used another formula. now my...
18. ### Why is higher density causing higher surface gravity?

Normal density of Earth is 5,5 tons/m3 and surface gravity is 9,8 m/s and. But if we would compress mass of Earth to 50 km diameter, we would get density 1,4 mil tons/m3 and surface gravity would be 158 860 m/s. I know the math, in basic gravity equotation F=Gm1m2/r2 with decreasing r you get...
19. ### Can temperature affect the mass of water

Hi there guys, I'm conducting an experiment to calculate the mass flow rate of water. Bellow is a copy of the procedure: 1) Weigh the mass in kg of a container 2) Connect a flow meter to a tap (any source) with a pipe and insure the departure pipe goes into a sink 3) Open the tap an increase...
20. ### Finding the Density of a given object

The density of an object equals its mass divided by its volume. The mass of Earth is 6x10e+24 and its radius is 4000 miles (1.61km = 1mile). What is the density of the Earth in kg/m^3? V=4/3pi(r)^3. D=M/V Converting 4000 to Km, I get 6400. After plugging it into the Volume equation, I end up...
21. ### Schwarzschild, Singularity, Density

Dear PF Forum, I have a question about the size of "singularity" This question has already been asked here, Question about Schwarzschild radius But what I want to know is this density thing that I'd like a confirmation. Actually it's 2.9511896078372906 KM according to his...
22. ### How does density affect thermal conductivity?

Since the flow of heat in solids happens due to the collision of the molecules with each other, thereby increasing their internal energy, a higher denser material will have molecules closer, does it mean that the thermal conductivity of high density materials will be higher than the lower...
23. ### Density of Water

Homework Statement A river car ferry boat has a uniform cross sectional area in the region of the water line of 720m^2. If sixteen cars of average mass 1100kg are driven on board, find the extra depth to which the boat will sink into the water. Homework Equations Density= m/V Density= m/Area X...
24. ### What's the chemical formula of cement and resin?

Hi, i need to know the chemical formula of cement and resin and their densities. can someone help me, please????????????????? thank you in advance !!!
25. ### Force in Varying Places in a Swimming Pool

Homework Statement A swimming pool has dimensions 25 m x 10 m x 3m (length x width x height.) When it is filled with water, what is the force on the bottom (Fb) of the pool? On the long side (Fl)? On the short sides (Fw)? (note that integrals are required.) If you are concerned with whether or...
26. ### Are density and resistivity proportional?

Today while reading a book i read that conductance of a metal depends on its density. But it is also dependent on its resistivity. Does that mean that resistivity and conductivity are proportional to each other?
27. ### Planet density -- no idea what to do

Homework Statement [/B] Consider a spherical planet of uniform density ρ. The distance from the planet's center to its surface (i.e., the planet's radius) is Rp. An object is located a distance Rfrom the center of the planet, where R<Rp. (The object is located inside of the planet.) Find a...
28. ### The possible effects on the water level

Homework Statement A small solid sphere of mass M0, of radius R0, and of uniform density ρ0 is placed in a large bowl containing water. It floats and the level of the water in the dish is L. Given the information below, determine the possible effects on the water level L, (R-Rises, F-Falls...
29. ### Finding vapour pressure using compressibility chart

Homework Statement I was asked to find the vapour pressure and saturated liquid molar density of propane at 263.15K using a generalised compressibility chart. (not allowed to use NIST or steam tables either, the chart i was given does not have reduced volume lines) Homework Equations Tr=T/Tc...
30. ### Calculation of the force exerted by a liquid

Question: The height of the given vessel is h,and the width of the given vessel is b (as given in the diagram). The density of the liquid is r.Find the force exerted by the liquid on the slant wall. Relevant formulae : P = F/A F = Vdg An attempt at the solution...