Hot Definition and 572 Threads

Dear all! Somebody, please tell me which crystal is soluble in hot water but not in cold water. I am looking for some crystalline chemicals which are strong enough to bind something like glass beads. As I mentioned, it should be highly soluble in hot water (or change into liquid on high...

I've noticed on my 2004 Honda Accord that my back left rim gets unusually hot (hard to touch and can feel the radiation) and there is some smell of burning rubber. Any ideas?

Good Morning Sirs, it seems to be surprisingly hard to get the numbers of a mystery: How fast expand hot rocket exhaust gases into empty space? Of course aside from its exit velocity! Does the expansion interfere with the impulse direction? I.e. is the impulse omnidirectional effective...

Homework Statement I'm doing a final project for my probability and statistics class that involves analyzing data on the sodium (mg/hot dog) and calories contained in each of 54 major hot dog brands. The hot dogs are classified by type: beef, poultry, and meat (mostly pork and beef). 20...

Homework Statement I want to find all acting forces on a hot air balloon rising form the ground. Volume and mass of balloon are given. Homework Equations F=mg F_{b}=ρVg The Attempt at a Solution Here is my free-body diagram; There are three acting forces: 1) F_1 = mg...

does ac current always flows from hot to neutral wire.if so where is the end of the neutral wire?

let say i have a horizontal wire of alumel(or steel or what ever), the thermal conductivity is 30 w/m^2/k. let say D=0.4mm one end of the wire at 1000 degree c ( so like submerge in a cement which is at 1000 c). how long do i need wire to horizontaly in free air so that the cold end is at 100...

I am thinking about solar water heating. The way that the system gathers heat is by moving any heated water into into the cylinder where it rises to the top and cold water is taken from the bottom of the cylinder and moved through the heating panel. Because the hot water will always rise...

I had meet a problem when I study the concept of the hot air balloon. The equation was giving Load = P*V*(1/TempAir - 1/TempBalloon)/R Then I reverse to TempBalloon = 1/[1/TempAir -Load*R/(P*V)] When the volume is less then 1m^3, the temperature calculated giving negative temperature...

So for a class I am designing a solar dehydrator and I want to know how fast the hot air will rise out of the dehydrator. For calculation purposes assume the hot air is 120°F @ 30% relative humidity (23 g/m3) and rising through a tube (if necessary assume the tube is 4 in. in diameter), the...

Homework Statement If you want a pot that will got hot as quick as possible and have a cooking surface that stays as hot as possible when heated what should the pot look like? Homework Equations The Attempt at a Solution I said that the pot should have a black exterior because...

Hi, I have to make the classic egg drop contraption but we're only allowed to use plastic drinking straws, index cards, and hot glue. the width also has to be smaller than 4x4 inches but it can be as tall as we want it to be (but preferably small) and it has to have a door of some sort...

I'm a scuba diver - diving since the 1960's. For more years than I'd like to admit, I've wondered why tanks get hot when you fill them from other high pressure tanks. I've seen it happen with "empty" scuba tanks (really at atmospheric pressure, temp). And with vacuum evacuated oxygen tanks...

I am making my first zvs driver and when I got it "finished" all it did was get my inductor and mosfets hot, the screwdriver I had in the heater did nothing. I killed the power before any damage was done, I hope. My mosfets are 2 IRFP250n's and I am powering it with a 12V 4A battery charger. My...

I've been thinking about this now and then, when boiling water. As the water becomes hotter the bubbles are rising in increasing numbers. The bubbles seem to either repel each other or merge to form bigger bubbles (or pop on contact) and then they seem to be moving toward the edge of the pot...

Homework Statement I have a balloon with a volume of 500m3 Outside air temp of 300K Mass to lift of 300kg Molar mass of air is 28 g/mol (I didn't end up using this) I am to find the temperature inside the balloon to barely lift the given mass. I have apparently forgotten everything...

Homework Statement I need to find out which freezes faster--hot or cold water--without doing a lab. Just by thinking and considering laws and theories and properties we have learned about. Homework Equations N/A The Attempt at a Solution It seems like it would be cold water since...

So this isn't homework, but it is for a class and I don't know how to go about this... I have to figure out if hot or cold water freezes faster. Any ideas?

When in reality, blue light is the higher energy.

An object (a tin can for example) orbiting the Sun at about the same distance as the Earth would be what temperature?

Why actually does "hot" water freeze before cold water? This sounds very basic but believe me I can't come up with a single feasible reason

Just got back home from the Kona side of Hawai'i. Wow. What a freakishly cool place that is! Day one, snorkeling. Saw so many fish...blue, yellow, stripes, red, dots, skinny, long, buck-toothed, bug-eyed, orange, green,...wow. Just, wow. Day two, long hike along beach. Admired the flowers...

I had read an article about a hot air balloon, when coming into balloon shape design, I had question on it. For best shape of the air balloon was the tear drop shape, but I do not know what is the physics behind it. From the article I read is about the pressure vector, and he is using an...

I was just bored during a lecture and started dozing of, then I had an idea of how heat travels. I tried searching in google if I was right, but I didn't know what to type (I tried stuff to do with second law of thermo, and IR photons traveling but couldn't find anything). So yeah I thought...

In Wikipedia page of Diurnal Temperature variation, there is a statement as following: "As solar energy strikes the earth’s surface each morning, a shallow (1–3 cm) layer of air directly above the ground is heated by conduction. Heat exchange between this shallow layer of warm air and the cooler...

Hi, and thanks for your expert opinions in advance. I'm working on a theoretical scenario of a flue gas funnel. Assuming hot air is rising from a funnel at a constant rate. Would the hot air rise faster if water droplets were sprayed at the top of the funnel, hence lowering the air temperature...

hello I have a question: i am trying to understand how we find out that the curvature of the universe is zero using the angular size of the hot spots of the d microwave background radiation. http://scienceblogs.com/startswithabang/2012/07/18/how-big-is-the-entire-universe/ there is a...

What do we feel when we say something is "hot"? So recently I had learned that temperature is just the average kinetic energy in the system, the more KE in the system particles the higher the temperature, KE is mv^2/2 meaning that temperature is just really the average of how much the particles...

Hi! I have this experiment, that keeps getting me frustrated. The experiment is simple: We have hot water and a long plastic tube with one end closed. We simply measure how much water is in the tube and from that we get the water volume (water is in cylinder shape). But there is something I...

"Food" Hot Plate vs "Science" Hot Plate I want to pick up a cheap hot plate for doing high school level demonstrations in chemistry. Is there any reason getting a normal hot plate would be a bad idea? Like this one? Thanks.

could anyone explain how to determine the flow rate of the hot water recirculation pump for water heater in domestic water supply?

Homework Statement A good estimate for the volume of a particular hot air balloon is 2800 m3. Suppose the total load (passengers, fuel, balloon fabric, etc.) on a hot air balloon is 724 kg. In preparing to launch, the pilot heats the air inside to an average temperature of 210 oC, giving it...

I am looking for shear modulus (G) for Nitronic 50 or XM-19 High strength hot rolled condition UNS - S20910 and ASTM A276-10 it is surprising for me that material standards like ASME or ASTM does not provide shear modulus data..? even checked "http://www.keytometals.com" and...

Homework Statement A hot-air balloon is rising upward with a constant speed of 2.51m/s. When the balloon is 3.01m above the ground, the balloonist accidentally drops a compass over the side of the balloon. How much time elapses before the compass hits the ground? Homework Equations...

Homework Statement A hot-air balloon has just lifted off and is rising at a constant rate of 2.3m/s. Suddenly, one of the passengers realizes she has left her camera on the ground. A friend picks it up and tosses it straight upward with an initial speed of 14m/s. If the passenger is 2.5m...

My understanding of glass is that it is transparent because photons do not have enough energy to raise the electrons in the atoms to the next energy level, thus the photon is not absorbed thus it gets through and we see it as light. But if the photon isn't absorbed, thus not leaving it's...

from a layperson's perspective - if a supermassive black hole is more massive than a million suns then why is it cold? An answer in plain english is truly appreciated for the layperson like me.

I'm working on a sci-fi / noir / mystery novel for my thesis, and I've endowed my femme fatale heroine with the ability to conjure traversable wormholes. It's important that she be able to do this without the aid of any machine or finite quantity of exotic matter that she would have to...

Hello all. Consider the case whereby one brings out a cold drink on a hot day. Why do water droplets form on the surface of the cold glass? I would think that when water molecules in the gaseous state collide with the glass surface, they transfer some energy into the glass. Therefore by the...

Just a quick question relating to thermal equilibrium between a hot and cold body. If a hot body and cold (closed systems) are opened up to each other, the thermal energy will be transfer from the hot body to cold body through conduction. So even when thermal equilibrium is reached, the...

Homework Statement A heat engine operating between freezing and boling points of water takes 20 cycles to raise a mass of 1000kg through a height of 3m. Calculate the minimum energy per cycle that must be extracted from the hot reservoir in order to achieve this. Homework Equations...

I have hydraulic system that lift something heavier than 1 tonne. My problem is the hydraulic fluid always get so hot and sometimes because of the heat it could not lift its load (loss power). I tried to increase its flow rate and its worked for now. But it way above the permitted flow rate...

All, I am an engineer that occasionally needs to modify or rework circuit boards. I have a hot air rework station that uses a diaphragm pump to push air through a heating element. The result is air up to 550 degrees celcius. I can effectively rework most circuit boards. Unfortunately the...

Hello, My attic gets blazing hot in the summer days, i have installed more than enough electric fans, my house just never gets shaded and the attic is quite small. my first idea was to build a giant shade producing robot. after that, I decided to vent all of my A/C air into the attic...

Hello friends, I am into modelling of electric hot water tank which is vertical and has the capacity of 120 litres. I just assumed certain charactersitics of an existing heater so as to be more realistic in my approach. Now I am facing certain troubles in my calculations, if you know please...

Hi all, I'm in the process of rebuilding a land-based boat house that was leveled in a tornado. This is one of the old styles with the railroad tracks and a tram to hoist the boat in/out of the lake. The tram/winch motor has to be replaced. It is single phase 240V. As best I can tell, the...

I've just set a solar thermal array for research for my thesis. I would like to simulate different usage patterns to see how the system performs. I'm doing this using a Arduino with temperature sensors at the top hot the tank and on the cold supply which will then control a motorised valve which...

So a sadistic friend of mine posed this question: Of course this question can be thought of in two ways: a) would the surface still be hot enough at the bottom or b) would the interior be hot enough at the bottom (since the coals would probably break, its a relevant question). At the time...

Hot water is heavier than cold water. If density is decreasing means its cover area is also increasing, and weight is irrelative to the area body occupies. Isn't it? W=mg, to vary the weight we have to cop with its mass and gravity. As gravity is constant then is it the mass of the water...

Does temperature affect the health benefits provided by drinking tea?