So, this is a physics question I'm having some serious trouble with, help would be appreciated. Here's the question in all its detail:
A vibrating 400Hz tuning fork is placed in pure distilled water.
a) What are the frequency and the wavelength (in metres) of the sound waves produced within the water at 0 degrees C?
b) What would be the frequency and the wavelength in the adjacent air, if the sounds waves moved from the water into the air at 0 degrees C?
That's the question, I got the second half already...I think, but I can't figure out a) at all.
The equations we have are :
frequency = cycles/time
Period = time/cycles
Speed = frequency x wavelength
Speed = distance/time
Speed of Sound in Air = (332+(0.6xTemperature))
I have the answers in my text if anyone could get anywhere backwards.
Any help would be much appreciated.
What are the frequency and the wavelength of the sound waves produced in water at 0 degrees C?
I can't understand this question. Is the tuning fork totally immersed in the water? Then its frequency will be radically changed and the oscillation highly damped due to the water's inertia, relative incompressibility and resistance to motion. There's no way to compute its frequency without having a lot more information (at a minimum, details about the mass, size %26amp; shape of the tuning fork) and the calculation would be complex and difficult.
OK, so let's suppose its vibration is coupled to the water without beng immersed. Then it oscillates at 400 Hz, and this is the frequency of the sound in the water. The wavelength is then a trivial calculation.
Surely I'm missing something. I think you should provide the answer (via the "add details" option) and see what people think then.
EDIT: Since you added the answers, there's no disagreement on the frequency. The wavelength in any medium is the speed divided by the frequency, so there's no disagreement on the wavelength in air. However, the speed of sound in water is a parameter that many physicists have attempted to formulate. The generally agreed value at 0C is about 1430 m/s. Using the web page given below and the Marszak interactive calculator available there, I get 1402.385 m/s, which yields a wavelength of 1402.385/400 = 3.505963 m. (The other calculators on that page all agreed on the speed within 0.003 m/s.) The textbook's answer of 3.83 m implies a speed of 1532 m/s, which the Marszak calculator equates to a temperature of 42C! I think the textbook's author(s) have some explaining to do.
Reply:Property of water is just the velocity of vibrations in it. Whatever frequency you make its particles vibrate waves with wavelength equal to velocity divided by frequency will be produced in infinite expanse of water. If it is limited expanse then waves of wavelength which fit in full measure of half wavelengths can be produced so that there is node always at the end of the water where it touches the container. then various modes or frequencies will be produced to be obtained by dividing velocity by wavelength. I have told you physics now you evaluate and find the answers or put some related query.
Monday, May 24, 2010
What makes a squealing noise when I turn on my vehicle A/C?
I have a 1999 Jeep Cherokee 4.0L, AT, 4WD and when I turn on my air conditioner, it squeals for a about 15 seconds then goes quiet. What is causing this? The A/C works fine, it just makes this noise when I first turn it on.
What makes a squealing noise when I turn on my vehicle A/C?
Sounds like a little belt slip. When the compressor engages it creates a lot of drag all of the sudden. That can cause an older belt or a belt with too little tension on it to slip.
Reply:two things..pick the winner.
stretched belt.
compressor giving up.(ester oil and/or clutch.)
hint...clutch slip.adjusting gap.
Reply:AC belt is slipping. The easiest and cheapest way to fix this is to run the ac, and spray silicone on the spinning belt. Silicone will condition the belt, help it grab the pullies, and most of all, clean the small amount of oil you have on the belt which is causing the squeal. If you don't have Silicone, Armor-ALL is the same thing.
Marty
Reply:The belt is sliding for a few seconds before it grips. You can try tightening the belt or replacing it. Autozone, Advance Auto, they all carry a belt conditioner that prevents squeaking
garden design
What makes a squealing noise when I turn on my vehicle A/C?
Sounds like a little belt slip. When the compressor engages it creates a lot of drag all of the sudden. That can cause an older belt or a belt with too little tension on it to slip.
Reply:two things..pick the winner.
stretched belt.
compressor giving up.(ester oil and/or clutch.)
hint...clutch slip.adjusting gap.
Reply:AC belt is slipping. The easiest and cheapest way to fix this is to run the ac, and spray silicone on the spinning belt. Silicone will condition the belt, help it grab the pullies, and most of all, clean the small amount of oil you have on the belt which is causing the squeal. If you don't have Silicone, Armor-ALL is the same thing.
Marty
Reply:The belt is sliding for a few seconds before it grips. You can try tightening the belt or replacing it. Autozone, Advance Auto, they all carry a belt conditioner that prevents squeaking
garden design
Could something be wrong with the thermostat that controls central/heating a/c and heater unit?
It has started clicking every time it comes on or goes off. Could there be something wrong with the relay switch? Do I need to have an a/c repairman come look at it? We only had the digital thermostat installed about a month ago. I noticed that it began clicking about a week ago.
Could something be wrong with the thermostat that controls central/heating a/c and heater unit?
Some digital t-stats do make a clicking noise when they activate the unit. But, if yours is doing something above and beyond what it did for the first few weeks you had it, I would call the people that installed it and talk to them. If it was done by an a/c company they should stand behind their product. Other than the clicking, does it seem to be working properly? When you call the a/c people, give them any info you can on what it's doing differently. Good luck.
Reply:If it was installed by a professional person, call them back and tell them what is happening. It should have a warranty included.
Reply:this is usually a sign that the heat anticipator is either set wrong or screwed...if it is a digital stat...it should be able to be changed by the set up menus or just go through the manual...if it is a mechanical stat then it is either screwed or someone has taken the cover off and moved the heat anticipator dial type setting...stats are cheap if you can't figure it out get a new one. keep in mind that if it is still operating the system properly then there probably isn't anything wrong with it its just that you never noticed the "clicking" before...my possible problem suggestions only apply if you find the system to be cycling erratically
Could something be wrong with the thermostat that controls central/heating a/c and heater unit?
Some digital t-stats do make a clicking noise when they activate the unit. But, if yours is doing something above and beyond what it did for the first few weeks you had it, I would call the people that installed it and talk to them. If it was done by an a/c company they should stand behind their product. Other than the clicking, does it seem to be working properly? When you call the a/c people, give them any info you can on what it's doing differently. Good luck.
Reply:If it was installed by a professional person, call them back and tell them what is happening. It should have a warranty included.
Reply:this is usually a sign that the heat anticipator is either set wrong or screwed...if it is a digital stat...it should be able to be changed by the set up menus or just go through the manual...if it is a mechanical stat then it is either screwed or someone has taken the cover off and moved the heat anticipator dial type setting...stats are cheap if you can't figure it out get a new one. keep in mind that if it is still operating the system properly then there probably isn't anything wrong with it its just that you never noticed the "clicking" before...my possible problem suggestions only apply if you find the system to be cycling erratically
What do the letters 'c.f.' represent at the beginning of a citation in a journal article?
I am writing a research paper for a psychology paper. One of the citations is (c.f., Ferrari, Johnson...). Have not seen this before.
What do the letters 'c.f.' represent at the beginning of a citation in a journal article?
Cited From
What do the letters 'c.f.' represent at the beginning of a citation in a journal article?
Cited From
Fuel Economy of the C-130 Hercules Airplane?
After listening to NPR on the C-130 Hercules fuel economy @ 3 gallons to the mile, I find that hard to believe. Can this be confirmed? I had no success with my internet research on this subject.
Fuel Economy of the C-130 Hercules Airplane?
Bottom line is that those figures are close for reasonable loads, a bit worse with full load and a lot better when you fly empty and slow.
Maximum useable fuel on a C-130 is around 60,000 pounds, fuel density for Jet-A or JP8 is around 6.74 lb/gallon and that gives us around 8900 gallons. The total fuel load it 45000 internal and 18700 external, so that's 63700 and would give us a total of 9450 gallons (rather than the useable limit).
Let's be kind and work with the useable fuel load and leave the other two tons alone.
With full load the range is around 2400 miles, 2500 with 25000 pounds and around 5200 empty.
3.7 gallons/mile at full load
3.6 gallons/mile with 25,000 pounds
1.7 gallons/mile with no load
Reply:The Allison T56 burns about 1500 pounds per hour so in cruise:
1500 X 4 engines = 6000pph / ~7 lbs per gallon = 857 gallons per hour.
The C-130H has a cruise speed of 336MPH so
336MPH/857 GPH = 0.392 MPG or about 2.6 gallons per mile.
Reply:yeh its about right
Fuel Economy of the C-130 Hercules Airplane?
Bottom line is that those figures are close for reasonable loads, a bit worse with full load and a lot better when you fly empty and slow.
Maximum useable fuel on a C-130 is around 60,000 pounds, fuel density for Jet-A or JP8 is around 6.74 lb/gallon and that gives us around 8900 gallons. The total fuel load it 45000 internal and 18700 external, so that's 63700 and would give us a total of 9450 gallons (rather than the useable limit).
Let's be kind and work with the useable fuel load and leave the other two tons alone.
With full load the range is around 2400 miles, 2500 with 25000 pounds and around 5200 empty.
3.7 gallons/mile at full load
3.6 gallons/mile with 25,000 pounds
1.7 gallons/mile with no load
Reply:The Allison T56 burns about 1500 pounds per hour so in cruise:
1500 X 4 engines = 6000pph / ~7 lbs per gallon = 857 gallons per hour.
The C-130H has a cruise speed of 336MPH so
336MPH/857 GPH = 0.392 MPG or about 2.6 gallons per mile.
Reply:yeh its about right
What if you do not put an Air Filter in your central A/C?
The past people who have lived in the home I live in now did not put an air filter in the central A/C (A large square whole that sucks the hot air on the ceiling). I suspected this because when I started using it and later notice there was no filter. If thats the case, would this cause the dust to clog other vents around that goes to other rooms around the house? If so, how do I clean it out? Is it possible to do it yourself or will I need to hire someone? One of my rooms in the house does not have good ventalation and it gets hot. Also, the thermostat says "Replace Filter" even after I replace it with a brand new one.
What if you do not put an Air Filter in your central A/C?
Always use a filter. The dust and dirt will also clog the A/C condenser and cause it to run inefficiently and not cool the air well.
Reply:the filter is used to protect the A.C. unit from clogging,, not the duct work,, without a filter the fins on your A.C. unit will clog and greatly reduce its cooling ability,,you need to have someone check our unit!! a missing filter will not affect the duct work as that is on the other (output) side of the A.C.!!!!
Reply:um lets see here. Your air isn't gonna be clean and the dirty air is going to clog the ducts. Yeah so um i would put in a filter
Reply:The simple answer is to call a professional.
You cannot do this job right and it needs to be done.
The cost of trying to keep your house cool will pay for this service.
I am a chemical engineer.
A slight amount of dust on your coils will dramatically increase your expense (Same with the fridge). You need the ducts cleaned and the ac system serviced before you burn it up.
Reply:I would say yes
Reply:You need a filter to keep dust and dirt out of the evaporator coils, not the condenser- the condenser is outside. The fins on the evaporator will clog and cause a reduction in air flow for both the furnace and the AC. This will cause the coil to freeze up during the cooling months. It will also help to keep small dust particles from being circulated throughout the house. The reason the thermostat says replace filter is because of an already reduced air-flow. This is measured across the evap coils, you need to have them cleaned by a HVAC tech. You can clean the ducts yourself providing you have the proper vacuum to reach all thew way in, any amount that you can clean will still be better than nothing. try to partially close other vents in order to "push" more air to your room that gets the worst air flow. You can balence the entire house this way.
flower pictures
What if you do not put an Air Filter in your central A/C?
Always use a filter. The dust and dirt will also clog the A/C condenser and cause it to run inefficiently and not cool the air well.
Reply:the filter is used to protect the A.C. unit from clogging,, not the duct work,, without a filter the fins on your A.C. unit will clog and greatly reduce its cooling ability,,you need to have someone check our unit!! a missing filter will not affect the duct work as that is on the other (output) side of the A.C.!!!!
Reply:um lets see here. Your air isn't gonna be clean and the dirty air is going to clog the ducts. Yeah so um i would put in a filter
Reply:The simple answer is to call a professional.
You cannot do this job right and it needs to be done.
The cost of trying to keep your house cool will pay for this service.
I am a chemical engineer.
A slight amount of dust on your coils will dramatically increase your expense (Same with the fridge). You need the ducts cleaned and the ac system serviced before you burn it up.
Reply:I would say yes
Reply:You need a filter to keep dust and dirt out of the evaporator coils, not the condenser- the condenser is outside. The fins on the evaporator will clog and cause a reduction in air flow for both the furnace and the AC. This will cause the coil to freeze up during the cooling months. It will also help to keep small dust particles from being circulated throughout the house. The reason the thermostat says replace filter is because of an already reduced air-flow. This is measured across the evap coils, you need to have them cleaned by a HVAC tech. You can clean the ducts yourself providing you have the proper vacuum to reach all thew way in, any amount that you can clean will still be better than nothing. try to partially close other vents in order to "push" more air to your room that gets the worst air flow. You can balence the entire house this way.
flower pictures
How often do 1st-time moms have natural births as opposed to C-sections?
I have so many friends who had C-sections their 1st time. I want to know, is this common/normal/more probable than a natural (vaginal) birth?
How often do 1st-time moms have natural births as opposed to C-sections?
In some places (ahem New Jersey I'm looking at you) the c-section rates for first time moms are up to 50%. Overall the rates for HOSPITAL births in the US are around 30%.
There are however a lot of things you can do to NOT get a c-section:
*The more information you have the less likely you are to get a c-section
*Having a doula reduces your risk
*Not having an epidural reduces your risk.
*Having a midwife reduces your risks more
*Having a homebirth can reduce your risks to 10% or less with the right provider.
NEVER induce, except possibly for preeclampsia or HELLP. Most reasons for induction are complete BS. DO NOT allow an IV, if you do make sure no one gets anywhere near it. Women are often given pitocin without their knowlege, many former OBs have spoken out about it.
Reply:You can ask at your hospital or your OB office, as it varies depending on where you live. My hospital was between 25%-30%, which I think is too high! I had a natural birth. I was lucky, my doctor let me puch for 4.5 hours. Some doctors send you for a C-Section after a certain amount of time, like 3 hours.
Reply:I second what lilly said- if you get induced you double the risk of having a c-section. Many babies, the first time, go over their due date, and these days doctors are more likely to induce you for any little reason. Although I should have probably waited a couple days, I was scheduled for an induction only one day after my due date and, of course, ended up having a c-section. I definitely think more women end of having them because of inductions.
Reply:C-sections in the US are about 30% of all births. So, I'm sure there's more first time moms having natural birth. I'm 43 and had my first child, my son when I was 42. I had a c-section due to the blood thinners i was taking required a planned birth, along with some other health issues that made natural childbirth unavailable to me. I'm kind of glad, because I don't think i could have handled the natural birth had I been able because i was so scared something would go wrong. I so wanted this child as I never thought i could have any before. I was afraid I'd mess up somehow. Silly of me, but I felt like that.
Reply:I had a c- section my first time. I had a fibroid tumor so not sure if that had anything to do with it but I just didn't dialate and the cord was around the baby's neck so the Dr decided that a c-section was the best way to go.
Reply:I've read that 1 in 3 births (in the US) are C-sections. And, having your labor induced GREATLY increases the chances that the birth will be via C-section.
When you are 'shopping around' for a doctor/hospital, ask about the percentage of pregancies that end in C-section there. Some places have a better track record than others.
Reply:I had a natural birth. My water was broke at 10:30 A.M. and I had her at 3:51 P.M.! I pushed for probably 10-15 mins and she was out! She was only 6 lbs 1 ounce..and was almost too big for the birth canal!
Reply:I had a emergency c-section three weeks early for my daughter. She was breech and losing amniotic fluid and showing signs of distress
Reply:No. C-sections are medically necessary only. Most women have vaginal births. My SIL had a c-section with her first (and will with her second too) because she is VERY tiny and her body doesn't spread the way it should. She's under 100 lbs pre-pregnancy weight. You will have a vaginal birth unless something arises during labor and the baby needs to come out ASAP.
Reply:Had a natural birth with the first, and planning on a natural one at home with my second. Everything I've read about c-sections and drugs like Pitocin has scared the life out of me.
Reply:Well I had to have a c-section with my first (high blood pressure and the induction failed) but I was the first person in my family to have one. In fact I don't know anyone besides myself who's had one.
Reply:c sections are a quick way to get the baby out if labour is very long and stressful on the baby, most doctors will try for natural first and then csection is a last resort, i had a natural birth, vaginal and no drugs for all four of my kids most people deliver naturally
Reply:I had a natural birth. I didn't even really think about having a c-section, or the possibilities of me having one--I always thought they were for extreme circumstances.
Btw, not all first time labors are long either--mine was pretty short. I labored for three hours, pushed for 20 minutes. I might be an exception, and quick births kinda run in my family....my grandmother had one of her children in her kitchen! lol. Just thought I would share, since so many people like to spread horror stories about labor :p
Reply:c-sections are typically a last resort when a woman is unable to do it naturally or there is undue risk to the baby.
I would not say c-section is the norm, its more of a tool used to avoid the possibility of death.
Reply:It's odd that you know so many who had c-sections. Are you a lawyer? (being a female lawyer increases your chances for a c-section dramatically).
The primary c-section rate is about 20% nationally. That's the overall rate (all moms without prior c-section). I don't know the 1st time mom rate or if those stats are even kept.
In my state, the primary rate was 15% and is trending downwards. Part of this is due to more hospitals providing free doulas and/or trained nurse-midwives (stats show c-section rate among those who use these professionals is much lower).
Note: the higher percentage of c-sections usually quoted includes subsequent c-section as well.
How often do 1st-time moms have natural births as opposed to C-sections?
In some places (ahem New Jersey I'm looking at you) the c-section rates for first time moms are up to 50%. Overall the rates for HOSPITAL births in the US are around 30%.
There are however a lot of things you can do to NOT get a c-section:
*The more information you have the less likely you are to get a c-section
*Having a doula reduces your risk
*Not having an epidural reduces your risk.
*Having a midwife reduces your risks more
*Having a homebirth can reduce your risks to 10% or less with the right provider.
NEVER induce, except possibly for preeclampsia or HELLP. Most reasons for induction are complete BS. DO NOT allow an IV, if you do make sure no one gets anywhere near it. Women are often given pitocin without their knowlege, many former OBs have spoken out about it.
Reply:You can ask at your hospital or your OB office, as it varies depending on where you live. My hospital was between 25%-30%, which I think is too high! I had a natural birth. I was lucky, my doctor let me puch for 4.5 hours. Some doctors send you for a C-Section after a certain amount of time, like 3 hours.
Reply:I second what lilly said- if you get induced you double the risk of having a c-section. Many babies, the first time, go over their due date, and these days doctors are more likely to induce you for any little reason. Although I should have probably waited a couple days, I was scheduled for an induction only one day after my due date and, of course, ended up having a c-section. I definitely think more women end of having them because of inductions.
Reply:C-sections in the US are about 30% of all births. So, I'm sure there's more first time moms having natural birth. I'm 43 and had my first child, my son when I was 42. I had a c-section due to the blood thinners i was taking required a planned birth, along with some other health issues that made natural childbirth unavailable to me. I'm kind of glad, because I don't think i could have handled the natural birth had I been able because i was so scared something would go wrong. I so wanted this child as I never thought i could have any before. I was afraid I'd mess up somehow. Silly of me, but I felt like that.
Reply:I had a c- section my first time. I had a fibroid tumor so not sure if that had anything to do with it but I just didn't dialate and the cord was around the baby's neck so the Dr decided that a c-section was the best way to go.
Reply:I've read that 1 in 3 births (in the US) are C-sections. And, having your labor induced GREATLY increases the chances that the birth will be via C-section.
When you are 'shopping around' for a doctor/hospital, ask about the percentage of pregancies that end in C-section there. Some places have a better track record than others.
Reply:I had a natural birth. My water was broke at 10:30 A.M. and I had her at 3:51 P.M.! I pushed for probably 10-15 mins and she was out! She was only 6 lbs 1 ounce..and was almost too big for the birth canal!
Reply:I had a emergency c-section three weeks early for my daughter. She was breech and losing amniotic fluid and showing signs of distress
Reply:No. C-sections are medically necessary only. Most women have vaginal births. My SIL had a c-section with her first (and will with her second too) because she is VERY tiny and her body doesn't spread the way it should. She's under 100 lbs pre-pregnancy weight. You will have a vaginal birth unless something arises during labor and the baby needs to come out ASAP.
Reply:Had a natural birth with the first, and planning on a natural one at home with my second. Everything I've read about c-sections and drugs like Pitocin has scared the life out of me.
Reply:Well I had to have a c-section with my first (high blood pressure and the induction failed) but I was the first person in my family to have one. In fact I don't know anyone besides myself who's had one.
Reply:c sections are a quick way to get the baby out if labour is very long and stressful on the baby, most doctors will try for natural first and then csection is a last resort, i had a natural birth, vaginal and no drugs for all four of my kids most people deliver naturally
Reply:I had a natural birth. I didn't even really think about having a c-section, or the possibilities of me having one--I always thought they were for extreme circumstances.
Btw, not all first time labors are long either--mine was pretty short. I labored for three hours, pushed for 20 minutes. I might be an exception, and quick births kinda run in my family....my grandmother had one of her children in her kitchen! lol. Just thought I would share, since so many people like to spread horror stories about labor :p
Reply:c-sections are typically a last resort when a woman is unable to do it naturally or there is undue risk to the baby.
I would not say c-section is the norm, its more of a tool used to avoid the possibility of death.
Reply:It's odd that you know so many who had c-sections. Are you a lawyer? (being a female lawyer increases your chances for a c-section dramatically).
The primary c-section rate is about 20% nationally. That's the overall rate (all moms without prior c-section). I don't know the 1st time mom rate or if those stats are even kept.
In my state, the primary rate was 15% and is trending downwards. Part of this is due to more hospitals providing free doulas and/or trained nurse-midwives (stats show c-section rate among those who use these professionals is much lower).
Note: the higher percentage of c-sections usually quoted includes subsequent c-section as well.
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