by Ron Kurtus
Readers have sent in a total of 799 comments and questions on Physics issues. They are listed according to date.
You can read them to further your understanding of the subject.
|Applications of viscosity||Viscosity||India|
|Update Guyana voltage||AC World Voltages||Suriname|
|Equation different in textbook||Doppler Effect||India|
|Using static electricity to charge phone||Basics of Static Electricity||Egypt|
|Uses for friction||Uses of Friction||Nigeria|
|References on electrostatic painting||Uses for Static Electricity||Egypt|
|New Triboelectric idea||Static Electric Materials||USA|
|What do the signs mean||Force Between Two Objects||Australia|
|Difference in echo times||Sound Echoes||Tanzania|
|Electricity for water heater||AC Wiring||USA|
|Questions on electromagetism||Basics of Magnetism||India|
|Noise comes on every day||Noise Reduciton||UK|
|How do electromagnets work in railway signals?||Electromagnetic Devices||India|
|How does pressure affect a liquid?||Pressure||Ghana|
Applications of viscosity
April 18, 2017
Sir please explain: Applications of viscosity in our daily life in an easy way.
Kummari - India (28007)
Viscosity can be thought of as the "thickness" of a liquid or fluid. One application is in lubricating a machine. Oil or grease has a greater viscosity than water and thus it works better at reducing friction and wear between the parts.
High viscosity means the material is slow-flowing, like molasses or toothpaste. You wouldn't want them to have low viscosity, such that they were runny.
I hope that helps your understanding,
April 2, 2017
I am a writer of science topics and have a website www.science4fun.info/ which is about teaching the kids about science with interesting articles and easy-to-do experiments. its motive is to provide science education free of cost and free of ads to enhance the interest. I want to deliver my website to every science student. I will thankful to you, if you can check the website's physics section at http://science4fun.info/physics and include in your physics resource page under the name "Physics for Kids" for the students.
I look forward to hear from you soon. Thank you
Abdul Wahab - India (27980)
I added a link to Fun Science for Kids at Physics Resources. Best wishes for success with your website.
Update Guyana voltage
March 24, 2017
Re: World list of AC household voltages has an error:
Guyana 60Hz = correct but 240V? No Way.!
Some 110 or 120V . Check it out!
Happy to see a comprehensive AC voltages listing.
Jozef - Suriname (27956)
Thanks for the input. The standard AC voltage in Guyana is 220 or 240V. However, there are many areas in the country that use 110VAC.
I updated the list to reflect state both voltages.
Equation different in textbook
March 2, 2017
In textbook eq. is given in terms of v, but in your lesson its given in terms of lambda.
Rajendra prasad - India (27919)
The velocity of a waveform--especially for light or sound--is often designated as "c" instead of "v". Lambda represents the wavelength.
You can also rearrange the equation to be wavelength = velocity/frequency.
Also see Doppler Effect Equations for Sound.
Using static electricity to charge phone
February 24, 2017
if i somehow generated this static electricity, how would i use it for turning on something ?
and how much electricity needed to make a phone charger work for example ?
nada - Egypt (27904)
Static electricity is static and does not move like DC or AC electricity.
Most phone chargers use alternating current (AC) electricity to charge the batteries. However, there are some new chargers that use the wireless electricity signals to charge the batteries.
Static electricity can be used to generate sparks. That might be able to turn something on. But also, the sparks can cause damage to electrical devices.
Uses for friction
February 23, 2017
List 12 uses of friction and disadvantages of friction
ade - Nigeria (27902)
References on electrostatic painting
February 20, 2017
I am Working on A project On High Voltage Engineering and i need any Reference talking about Electrostatic Painting
Mahmoud - Egypt (27892)
Some websites explaining the basics of electrostatic painting are:
Electrostatic Spray Painting Basics Explained
How Does Electrostatic Spraying Work?
I hope that helps. Best wishes for success in your project.
New Triboelectric idea
February 20, 2017
Good Day to you sir,I have taken an interest on your webpage because I also work on Triboelectric generation techniques of my own that are considered totally outside of the box thinking. If you would be interested, I would very much like a moment of your time. THANK YOU
Benjamin - USA (27893)
It is good that you are coming up with some new applications.
I'm not sure if I could help you, but I'd be glad to take a look at your idea.
What do the signs mean
February 19, 2017
Hey I'm Aric and I'm trying to work out the gravitational attraction between the Sun and the Earth for homework
I just wanna know what the times, divide, plus and minus mean
Like as in;
* = Times?
/ = Divide/Fraction
- = Minus
and so on
Aric - Australia (27888)
The equation F = GMm/R^2 means G times M times m divided by R squared or R times R.
To answer your question:
a*b means a times b or multiply a times b
a/b is a divided by b
a - b is a minus b or subtract b from a
The big thing is to find the mass of the Sun and of the Earth, as well as the distance between them.
I hope that helps. Best wishes in getting the problem solved.
Difference in echo times
February 19, 2017
a helcopter is hovering at an altitude of 200 m above the surface of a lake. a speaker on the helcopter is sending out soundwaves,which are reflected from both the surface of the water and the bottom of the lake. if the difference in arrive times of the two echoes is measured tobe 0.24s, what is the depth of the lake?
(the atmopheric temperature is 20centgreds)
Toroma - Tanzania (27890)
Most of the sound would be reflected at the surface of the water. Only a very small amount of the sound would go into the water. Also much of the sound would be reflected at the surface when trying to go back into air. In other words, the amount of sound reflected off the bottom of the lake probably could not even be detected.
The speed of sound in air is 343 m/s. So, it would take 200/343 = 0.58 seconds for the sound to go from the water to the helicopter.
The speed of sound in water is 1484 m/s. The sound would have to go to the bottom of the lake and then back up, and then it would take 0.58 s to reach the helicopter. For the difference to be 0.24 s, the depth would be 1/2 of 1484 * 0.24 = 178.08 m.
I hope that helps.
Electricity for water heater
February 19, 2017
I just found that I have current in the system from the hot wire of the water heater to ground . On one 110 with it removed from the breaker I get a reading of 1.7 volts to ground. The other reads .8 volts to ground. We went to checking because the power bill has been high and though that the water heater might have gone back. This is a older home and has had several changes over years. What would be the best way to find out what is going on.
Thanks for you help
Ben - USA (27891)
Often older homes have their electrical wiring installed or fixed incorrectly. I'm not sure how you could get readings of only 1.7 volts unless you have your voltmeter set wrong or the voltages are not for heating the water.
Although you probably hate to spend the money, it is best to get an electrician take a look at things. There may be some other reasons your power bill has been high, especially if the increase is recent.
Best wishes on solving your problem.
Questions on electromagetism
February 17, 2017
1. Ratio of Core area & Poles face area.
2. What is ATTRACTION POWER?
3. If three sides of magnet is covered with non magnetic material will there be more force on pole faces.
4. Construction & operation details of
tks. rgds, Vish
Viswanatan - India (27886)
See our lessons on Electromagnetism. They should help answer some of your questions.
Noise comes on every day
February 16, 2017
Dear Sir, please can you help me with this.
I have a building site across the road from my house.
I arrived home one day to a sound which was like my washing machine emptying out.
Since then the sound has changed. The Council monitored low voltage sound waves in the house and a sound consultant monitored 40 to 60 hertz.
Could it be that instead of hearing something emptying I actually heard something being connected to my pipes.
The sound now changes at the same time every day and I get brief interference on my TV at this time.
My main problem is that it gives me headaches and hurts my ears.
Could this be from a drainage/sump pump? Please can you give me some advice. Thank you.
Ann - UK (27884)
I am sure such a noise would be annoying to you. If they are building something across the street from your house, it could be that they are turning on some equipment at the same time each day. They fact that your TV has brief interference points to some electrical switching on or off.
It would be worthwhile to go to the building site and ask if they turn on some equipment at that certain time. This could give you a clue as to the cause of the noise.
It is possible that they have something connected to water or sewage pipes that reach your house. It could be some vibration from equipment pressing against the pipes or even pumping or draining from the pipes.
You might have to ask a few people there, and hopefully someone will give you a clue as the the cause of the noise.
I hope that helps in solving your problem. Best wishes for getting rid of that noise.
How do electromagnets work in railway signals?
February 14, 2017
How electromagnet works in railway signals?
Harsh - India (27879)
Railway signals can be flashing lights or a moving barrier.
An electromagnet could be used as a solenoid to turn on or turn off the railway signals.
The barrier is usually moved by an electric motor.
How does pressure affect a liquid?
February 6, 2017
Give 3 ways on how pressure acts on liquid
Adu - Ghana (27860)
Pressure acts on a liquid in all directions. Pressure can also increase the temperature. Pressure only decreases the volume a small amount, if at all. Likewise, the temperature that the liquid changes to a solid is only slightly affected by pressure.
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