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Science Feedback

by Ron Kurtus

Readers have sent in a total of 4977 comments and questions on Science issues. They are listed according to date.

You can read them to further your understanding of the subject.



List of next 15 letters

Title

Topic

Country

Melting and boiling points of materials Kinetic Theory of Matter USA
 
Upstairs neighbor making noise on the floor Sound Detection USA
 
Problems with flyaway hair Reducing Static Electricity Shocks USA
 
Methods of discharging electroscope Uses for Static Electricity Zambia
 
Cancelling low frequency whispers Noise Cancellation USA
 
What is a mixture? General South Africa
 
Can't get rid of static cling Static Cling USA
 
Application of thermodynamics in engineering Thermodynamics Nigeria
 
Escape velocity equation seems wrong Gravitational Escape Velocity Derivation Nigeria
 
Used information for research Electromagnetism USA
 
Home oxygen safety Static Electric Materials USA
 
Finding the horizontal velocity Horizontal Motion Unaffected by Gravity USA
 
Are comments true for sliding friction? Sliding Friction Nigeria
 
Gravitation miscalculation Force Between Two Objects USA
 
Do forces cancel out? Centrifugal Force UK
 

Next 15 letters

 




First 15 letters


Kinetic Theory of Matter

Melting and boiling points of materials

January 30, 2016

Question

Hello! My name is Connor Feckett. I am a student at the School of Applied Research in Land O Lakes. I am currently working on a project about the changes in matter and using the scientific method. This project will include researching the different states of matter, kinetic theory of matter, melting and boiling points, as well as using the scientific method to predict if adding things to water may change its melting or boiling points. I am wondering if you could help direct me where to find the melting and boiling points of at least 5 different things. I appreciate your time. Thank you.

- USA (26732)

Answer

See Melting and Boiling Points of Common Materials for a comprehensive list.

Best wishes for success in your project.

PS: I'm originally from Wisconsin.

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Sound Detection

Upstairs neighbor making noise on the floor

January 29, 2016

Question

Hi,
I am looking for something that picks up sounds say through a ceiling. I have a very noisy neighbor and they drag furniture and drop things hard on the floor etc and I want to either record this or have it show on some sort of graph etc or both. Can you advise me on what type of device is the best for doing this? If so and know a link ,please send it to me. Anything will be greatly appreciated. I will use this to show the police,land lord and hosing authority on what is going on day after day after day.... Any info will help. Thank you.

Lorenz
Bmx4851@yahoo.com

Lorenz - USA (26729)

Answer

It can be very annoying when the neighbor above your place makes noises on the floor. I've had the same experience.

The police do not care to get involved, since the people aren't breaking any laws.

A good thing to do is to talk to the people upstairs and politely ask them to try to make less noise on the floor. They might then be more careful. If that doesn't work, you could talk to the landlord, but that may not do much good.

Recording the noise can be done with any digital recorder or tape recorder, but I think most people would take your word for the fact that it is annoying or bothersome.

Best wishes in solving your problem. In my case, I was glad when the people moved away.

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Reducing Static Electricity Shocks

Problems with flyaway hair

January 27, 2016

Question

The most problem I have is with my hair. It just flys and I can't get it to lay down. My hair is thin anyway and this makes it really difficult to handle.

Tresa - USA (26723)

Answer

See Controlling Flyaway Hair for some ideas. I hope that helps.

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Uses for Static Electricity

Methods of discharging electroscope

January 27, 2016

Question

What are the methods of discharging electroscope.

Douglas - Zambia (26724)

Answer

You want to draw off the excess changes in the electroscope by touching the metal bulb or disk. You can draw off the charges by touching with your finger or with a metal rod. See Detection of Static Electricity for more information.

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Noise Cancellation

Cancelling low frequency whispers

January 24, 2016

Question

How can someone cancel human speech, especially low frequency and low pitch whispers? Since spoken sounds contain many different wavelengths and frequencies it, in theory, should be easier to match a whisper with a 180 degree amplitude adjustment...is my thinking correct? Is there anyway to interfere with /cancel the 'sound' by altering electric or magnetic fields and what kinds of equipment could /would one use? Am I wrong thinking that speech can be manipulated(I.e. broadcast ) to travel long distance via radio waves within electromagnetic field? If so, would one alter near or far field and how? Please understand: I am exploring possible alternative solutions for me a more than one application/problem. Thanks

Justin - USA (26718)

Answer

If a microphone can record low frequency and low pitch whispers, those frequencies can be cancelled out. The electronics can filter the complex waveform into distinct frequencies and amplitudes. Of course, it isn't exact, but changing the phase of the the narrow frequency bands is enough to cancel much of the sound.

Whether the sound is loud or soft doesn't affect the cancellation.

The active noise cancellation electronics uses changing electric fields to cancel the signals. You can now buy an inexpensive set of noise cancelling earphones to examine and use the electronics.

Radio waves are electromagnetic waves within the radio frequency band.

Best wishes in creating alternative solutions.

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General

What is a mixture?

January 19, 2016

Question

What is a mixture

mbali - South Africa (26712)

Answer

A mixture is blending two dissimilar materials together. See Mixtures for more information.

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Static Cling

Can't get rid of static cling

January 19, 2016

Question

I washed and dried (laundromat: big mistake too hot) some synthetic tops that I love. They cling to themselves completely now and if I put them on, to my body. Did I completely destroy them? I've tried the hangers, washing them and not drying them, dryer sheets to no avail. Any more thoughts on how I might save them? Thanks.

Gale - USA (26714)

Answer

I've never heard that you couldn't get rid of static cling in synthetic clothes. I can't imagine what could have happened to the material.

One web page that might help is How to Cure a Bad Case of Static Cling. It might give you some other ideas to try.

Best wishes on solving the problem. Let me know how things turn out.

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Thermodynamics

Application of thermodynamics in engineering

January 18, 2016

Question

Good afternoon, please what are the application of thermodynamics to mechanical field (mechanical Engineering field)

Olushola - Nigeria (26705)

Answer

Thermodynamics principles are used by mechanical engineers in the fields of heat transfer and energy conversion. Mechanical engineers use thermo-science to design engines and power plants, heating, ventilation, and air-conditioning (HVAC) systems, heat exchangers, heat sinks, radiators, refrigeration, insulation, and others.

As an example, automotive engines convert chemical energy from the fuel into heat, and then into mechanical work that eventually turns the wheels.

I hope that helps.

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Gravitational Escape Velocity Derivation

Escape velocity equation seems wrong

January 18, 2016

Question

you wrote that ve = ??(2GM/Ri) but in my textbook I saw that ve = ?2gR

valentine - Nigeria (26708)

Answer

The equation ve = SQRT(2GM/Ri) is the escape velocity from the gravitation of any very large object, such as the Sun.

However, you can simplify the equation for the escape from the Earth as v = SQRT(2gR), where g is the acceleration due to gravity and R is the radius of the Earth. See Escape Velocity from Gravity - Common Escape Velocities paragraph.

I hope that clarifies things.

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Electromagnetism

Used information for research

January 13, 2016

Question

I used this page for research for my science fair project. Don't worry, I did not copy, but I do appreciate this page on electromagnetism.

Kelsey - USA (26690)

Answer

I'm glad the material was useful to you and your science fair project. It would be good to cite this website, as well as others where you got information in your report. That improves the validity of your experiment.

Best wishes for success in your project.

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Static Electric Materials

Home oxygen safety

January 12, 2016

Question

My husband is on oxygen and I am hoping that you can tell me what items in the home create static electricity so that I can remove and/or not use them. I am so afraid of starting a fire and am not well versed on this subject. Also, the room that I will be setting up for him soon has carpeting. Is there something (a liner or such) that I could place over the carpet to keep the static away? When you respond, would you please write something indicative of this subject in the email subject so that it does not become last in the junk mail? Thank you SO MUCH for your time!

Casaundra - USA (26685)

Answer

Home oxygen should be kept away from inflammable materials. A static spark nearby could cause problems. However, if you haven't had problems in your house from static sparks--like after walking on the carpet--there isn't that much of a risk.

The following websites give pointers on care that should be taken when using home oxygen: Oxygen safety and Important Safety Tips for Your Home Oxygen System.

Best wishes for a safe home and the good health of your husband.

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Horizontal Motion Unaffected by Gravity

Finding the horizontal velocity

January 11, 2016

Question

Is there a way to find an objects horizontal velocity of a falling projectile using conservation of momentum, given the mass of the object, distance traveled and original height? If there is could you explain how to use such an equation?
Thank you

- USA (26682)

Answer

The equation for the horizontal velocity as a function of mass, height, and distance traveled is v = x/SQRT(2y/g) where
v is the velocity
x is the distance traveled
y is the height
g is the acceleration due to gravity
SQRT is the square root sign.

See Effect of Gravity on Sideways Motion for details.

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Sliding Friction

Are comments true for sliding friction?

January 9, 2016

Question

are these below true of sliding friction?
-frictional force is independent of the area and dependent on the nature of the surfaces in contact.
-the frictional force is directly proportional to the normal force.

- Nigeria (26674)

Answer

The comments are true for sliding friction. Note that "normal force" is the force pushing the two objects together.

If you are able to read e-books, I can send you a file of the book either in the Kindle or in the EPUB format.

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Force Between Two Objects

Gravitation miscalculation

January 4, 2016

Question

The boy is 165lbs has a weight of about 740 Newtons and a mass of 70-kg not 7-kg.

Steve - USA (26661)

Answer

Thanks for noticing the miscalculation..

There is so much confusing between kg-mass and kg-force, that I put everything in terms of mass in the Gravitational Force Between Two Objects calculations.

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Centrifugal Force

Do forces cancel out?

December 24, 2015

Question

"A centrifugal force is the outward inertial force on an object moving along a curved path. An object will move in a curved path provided some force is preventing it from moving in a straight line, which is the centripetal force."

The above is incorrect. A rotating object "Exerts" a centripetal force, it is not subject to such a force. If a rotating object is acted upon by both a centripetal and a centrifugal force, which is what you are saying, these forces would cancel out.

Frank - UK (26648)

Answer

If an object is held to a rotating disk by friction or some other force, it will experience a centrifugal force that seems to pull it outward.

The friction or other force--such as a rope attached to the center of rotation--applies the centripetal force.

Once the friction is released, the object will fly outward in a straight line due to its inertia.

There is no such thing as a single force, according to Newton's Law of Action and Reaction. Thus the forces do not cancel out.

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