Water Definition and 1000 Threads

  1. L

    Position of the image of an object placed in water

    I tried using the formula for the refraction of a spherical lens ##\frac{n_1}{p}+\frac{n_2}{q}=\frac{n_2-n_1}{R}## consider each slab as a spherical lens with curvature ##R=\infty## and by doing that I get ##\frac{1.33}{10}+\frac{1.5}{q}=0\Leftrightarrow q\approx -11.3 cm##. Since the piece of...
  2. sophiecentaur

    Plumbing Finding a leak in a Central Heating system (water)

    It has to be going somewhere! The boiler pressure drops by about 0.5Bar every few weeks. I've looked at the radiators for signs of small leaks but I haven't been inside the boiler as yet because I only recently terminated a maintenance contract with British Gas. BG were not interested in a leak...
  3. bluesteels

    Quick question about the heat Q transferred between water and skin

    My work Q= 0.025 * 4190 * (34-100) = -6910 but on chegg but did they do Q= 0.025 * 4190 * (100-34) = 6910. I thought the initial is 100C and final is 34 because it goes from 100 to 34
  4. W

    Thermal Physics Problem -- Dropping a hot mass of iron into 20C water

    Hi, The solution for this question is thermal energy lost= thermal energy gained 0.200x450x(300-T)=1.0x4200x(T-20) T=26 degrees celcius. However, I am struggling to grasp why (300-T) is used. I have always known a change in something to be final - initial. Therefore change in T= Final-...
  5. P

    B How Does Ambient Temperature Affect Aquarium Water Temperature?

    Hello, I am in the process of trying to figure out the conditions required to heat an aquarium using the surrounding air. The first step is to figure out how to calculate the room temperature required to keep the aquarium at a desired temperature. I was drawn to this forum when I ran across...
  6. bluesteels

    Confusion about whether to use the specific heat of water or ice

    My thought process of how i do the ice melting part: (note I just ignore the copper/lead part cause I already know how to do that part) Q_ice + Q_melt + Q_liquid so, it 0.018(2100)T+0.16(4190)T+0.018(334*10^3) but on chegg they didn't use 2100 but they just use 4190 instead and I am confused...
  7. F

    How To Convert Kvs-Value For Water To Kvs For Gas?

    Hello, for an instrument I have given the Kvs-Value for water and I want to convert it to gas. Can someone help or explain the calculation? Of course I have the formulas for liquid and for gas KVs-calculation. How do I convert it? Thanks for the help Falko
  8. S

    I Why does light travel slower in water?

    I always thought it was from individual water molecules absorbing and reabsorbing light, but this explanation in a video from Fermilab is very strange to me . What is this "new wave" he speaks of; wouldn't it be light too? If so, then this light is now slower than the speed of light, which...
  9. E

    Theoretical reaction rate for water electrolysis

    So I'm designing a proces where carbondioxide is converted into methane using the Sabatier reaction. For this reaction hydrogen is required which I'm planning on producing using the electrolysis of water. But I'm having a problem where I need the speed of this reaction to determine the size of...
  10. T

    Mars - Igneous Rock, Exposed to Water, and with Organic Material

    A good candidate for the sample retrieval mission. https://www.nasa.gov/feature/jpl/nasa-s-perseverance-mars-rover-makes-surprising-discoveries
  11. W

    I The reflection of the sunset on the water is redder--Why?

    I presume that some kind of absorption occurs when the sunset is reflected on the water, but can anyone describe this in more detail?
  12. S

    I Water Tank Overflow Air Piston concept/question

    I am trying to determine the minimum piston weight/force that would be required to push the air from the air tank into the top of the supply tank, filling up the supply tank and purging the discarded water thru the outlet supply pipe. We can assume no friction loss and sufficient air in the air...
  13. D

    I A New Idea for the Origin of Earth's Water

    I will begin with the concept that the Moon was originally a rocky terrestrial planet that orbited at roughly one AU from the Sun and lost the majority of its lighter volatiles including water during the T-Tauri phase of the Sun's transition into a Main-Sequence yellow dwarf star. A similar...
  14. maistral

    A Shallow water equations evaluation

    Summary:: A little confusion on the momentum equation (I think). According to Wikipedia (I know, I just need basic resources for now), the conservative SWEs are : If I use product rules, I am supposed to get: For context, note that ρ is a constant and can be taken out (thus canceled out)...
  15. S

    MHB Calculating Total Area Under a Trapezoidal Curve for Water Tank Fill Time

  16. kyphysics

    Can You Add Water to a High Efficiency Washer (There is So Little)?

    I used a HE (high efficiency) washer for the first time today at a relative's house (they're gone on vacation, so no one "warned" me). I washed a "medium" load of clothes ("medium" for a traditional/regular washer) and to my utter shock, the water level was only about 1/5 or 1/4 (at most) of...
  17. A

    Supercritical Water Reactor: Density & Temperature Impact

    Hi, I'm working on an MCNPX design for the Supercritical Light Water Reactor, and I want to know how does the density of the water -which plays the role of the coolant and moderator- change with temperature? I think the pressure is fixed at 25MPa, but the temperature of the water may vary, Does...
  18. S

    Is electrolyte chemical consumed during alkaline water electrolysis?

    In alkaline water electrolysis you add Potassium hydroxide, or Sodium hydroxide to the water you want to turn into hydrogen and oksygen. But is the Potassium hydroxide, or Sodium hydroxide consumed during electrolysis and needs to be replaced? Or do you just have to keep adding water as it is...
  19. G

    Heating a steel spring then quenching in water

    Hi group, I heated a steel spring until red hot then plunged in water quenching it. My understanding is that quenching so quickly would have an effect of the grain size such that I would expect it to be much more brittle as with small grain there is much less plastic deformation possible (as...
  20. kyphysics

    Do You Call a Plumber if Washing Machine is Dripping Water in Tub?

    Two questions: 1.) If you have a washing machine that is dripping water into the tub (no leaks outside that I can see), would that typically be a problem that plumbers are called for or some other sort of repair/handyman/technician? 2.) Anyone know what's up with mine? IT WAS WORKING FINE...
  21. C

    The importance of water for life

    Hi PF, I'm teaching a college level introductory course about planet Earth and we are briefly discussing the importance of water for life. This is not covered in our textbook but I thought it was important to cover. I found some good resources...
  22. A

    Understanding MAL of Cadmium in Soft Water

    What does ‘MAL (is it Maltol) of cadmium’ in soft water mean?
  23. Dario56

    I How Does Surface Tension Balance Small Objects on Water Surface?

    When small object such as needle is put on the surface of water it displaces small amount of water which creates a depression under the object. Such depression increases surface area of the water because of which surface tension tends to decrease it. Explanation why surface tension balances the...
  24. S

    Help understanding refraction in water

    I recently had some trouble understanding refraction but after I finally understood where I went wrong (thanks to the people on this forum) I went back to my old lecture notes because I thought that what I recently learned didn't fit right with something that had previously been presented in my...
  25. B

    Cooling tower -- hot and cold water tanks

    Hi In some projects, I saw that hot and cold water tanks have been used for open circuit cooling towers. What is the need to use these tanks?
  26. X

    I How does the Lota Bowl water experiment work?

    Hello! Can anyone help me understand why this experience works this way? If we plug the hole on the left side, the water does not affect the cup that has the hole on the bottom. However, if we let go of this hole on the left side, the water will start to pour into the cup again. Is the law...
  27. L

    Which diagram of water molecules is correct?

    I've seen both types of diagrams when drawing covalent dot and cross diagrams. And some students that I teach said that the electrons should be on the circles. But I do know that this is actually showing the electron overlap and electron field and in reality electrons are not in circular orbits...
  28. K

    B Cheapest equipment to boil water at 60℃

    Water (any liquid) in a closed container boils when the vapor pressure of water (a property that depends on its temperature) equals the surrounding pressure. The vapor pressure of water at 60℃ is about ##1.99\times10^{4}## which is roughly 150 mm Hg.This principle is so simple, and yet, it is...
  29. RawPotatoes

    I Issue calculating water pressure due to the constriction of water flow

    For an experiment where I must be able to control the pressure i attached to a syringe a 'chamber'. The inner diameter of the syringe is 19.3 mm and i will fill water to 17 cm of the syringe bottom (i call this P1), the spout has a inner diameter of 2 mm and a length of 2 mm (i call this P2) and...
  30. N

    Chemistry Help with this interpolation (change in entropy while heating water)

    Hello, everyone :). I try to resolve this common problem. But, when i got in the interpolation of state 2, the values not make the sense. I have 25 psia and 75 F, but, in the superheated water table, there are not values with 25 psia (only 20 psia and 40 psia). And, the temperature values...
  31. Pim_Verwoerd

    Engineering What Is the Pressure After a Hydro Turbine?

    For an engineering project we have to make an energy storage system. We thought of something like a hydro dam. We were having a discussion about the pressure after the turbine in the hydro dam. The water immediately flows into the atmosphere ( so it falls down into a lake ). Can we then safely...
  32. C

    I Why does a drip of water into water make a noise?

    What is the 'gloop' noise; what actually makes the energy noise (from gravitational/kinetic into ... what transformation?), how is that transformed energy then coupled into a propagating wave in air? Further, whatever 'that' is, is it the same for an ocean wave, just godzilions of little drops...
  33. BillTre

    How surface water flows in the US

    Found this map website. Click on the map somewhere, and it will figure out the path surface water, from that point, would take, as it flows to the sea (or where-ever). It also makes a 3D fly over if you click the path. It doesn't show drainage basins, which would have been nice, but there...
  34. R

    Force of pressurized water exiting a hose or pipe?

    Well known examples of the force produced by pressurized water exiting a pipe: JetLev Water Propeled jet Pack. Hovering Car. I need to calculate the maximum for the thrust produced when the hose or pipe is bent rearward. Since this is similar to the case of a water bottle rocket, the guess...
  35. E

    B The Mysterious Water Bottle: Uncovering the Physics Behind It

    Today, I filled a bottle with water and I created a small hole beneath the bottle on the side. I realized that if I open the cock of the bottle, the water flowed out of the hole but if I close it, the water stopped flowing. WHY?
  36. SilverSoldier

    Approximations in Chemical Equilibrium (add a weak acid HA into pure water)

    Suppose we add a weak acid HA into pure water, so that upon addition its initial concentration is c. The following equilibria should establish in the system. $$\text{HA}+\text{H}_2\text{O}\rightleftharpoons\text{H}_3\text{O}^++\text{A}^-$$...
  37. R

    I Minimize supported weight of a water pipe

    I’m trying to calculate the weight I have to support at one end of a pipe with flowing water. So suppose you had a water pipe that extended from the ground upwards some distance away both horizontally and vertically, i.e., at an angle. Normally, you don’t have to worry about this issue because...
  38. K

    Why Isn't Water-Based Drink Hydration as Effective as Plain Water?

    I was taught that we need 8 cups of water every day to keep healthy, but why can't we have other drinks instead of distilled water? Many drinks today contain a lot of water, what is the logic when there is something else it is not considered to be as good as simple water?
  39. J

    B Discover the Reason Why Light Moves Slower in Water | Fermilab Video Explanation

    I watched a Fermilab video on light propagation in water: . He says (~) at time 7:50: "The oscillating electric field of the light make electrons in the glass move. These set up a second oscillating electric field that combines with the first to make a single oscillating field. That is the wave...
  40. person123

    I Water Waves Over Obstacles: Higher Frequencies Grow, Not Decay

    In general, it seems that higher frequencies of a wave dissipate more than lower frequencies. For sound waves, it explains why you can hear lower pitches from farther away. For a vibrating string or plate, the higher frequencies also dissipate first, with the fundamental fading last. For water...
  41. L

    Inlet Water Temp vs Feeder Water Temp in a BWR

    How can the inlet water temp be higher than the one of the feeder water that is in the reactor tank of a BWR?
  42. Istiak

    How much of the wooden timber was submerged in water?

    >Mass of a timber is $20 \ g$. And, density of that timber is $0.27 \ g/cc$. That timber was bind to a metallic materials and, it was released to $0.970 \ g/cc$ water. How much the wood was submerged in water? I was trying to solve the problem following way. $$F=Ah\rho g$$ $$=V\rho g$$ $$=V \...
  43. Ebi Rogha

    I Mass of Water Increasing with Heating

    Suppose we heat up a sealed container of water (no vapour escape), will it mass increase according to E=m.c^2 ?
  44. S

    Question about direction of movement of water molecule

    When the boat moves to the left, water molecules below it also move to the left. Is it correct to say the reason is because of Newton's 3rd law? Water molecules provide friction force to the boat so force on boat by water molecules is to the right. By Newton's 3rd law, there will be force on...
  45. MattGeo

    I What Keeps Water in a Straw When It's Removed from a Glass?

    For quite a long time I had just gone by the traditional explanation that when you place a straw vertically into water without fully submerging it and then you withdraw the straw from the water, the water column stays inside because the pressure from the atmosphere acting on the bottom of the...
  46. xpell

    Calculating Energy Released by Sodium Reacting with Water

    Hi! After watching a couple videos about the explosive reaction of sodium in freshwater and seawater, I felt curious and wanted to calculate how much energy is released. However, my Chemistry is super rusty and I think that my result is way too high (equivalent to almost 2 g of TNT per gram of...
  47. S

    Diesel Injector and Water Tube Boiler Back-Pressure

    Diesel injector: How much pressure relative to the maximum combustion chamber pressure during the sharpest phase of detonation does an injector need to be able to overcome to inject its full charge? How much overlap is typical between injection and detonation? Water-tube boiler: Are the water...
  48. E

    Engineering Thermodynamics homework help, water cooled air cooler

    I'm not looking for someone to tell me the answer, just help steer me in the right direction. I feel like I need to find the air density or air velocity at entry to proceed, but I'm unsure any help and guidance is greatly apricated!
  49. russ_watters

    Plumbing Water Softener Troubleshooting/Repair

    I have an older Morton System Saver water softener, model MSS20B. It's similar to THIS (pdf manual), but the buttons are different (it's 15 years old). It is currently flashing "VAC" (vacation mode) and "RCHG" (recharge mode) and is hissing like it's doing a recharge. At this point it has...
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