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Physics Feedback

by Ron Kurtus

Readers have sent in a total of 853 comments and questions on Physics 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

Ways to improve site AC USA
 
Why is a meat baked in a gas stove? General Belize
 
Coefficient of friction on an incline Friction India
 
Uses of harps in physics study Sounds with Musical Instruments Uganda
 
Why would plastic cause static electricity? Causes of Static Electricity USA
 
How do x-ray machines improve security? X-rays Canada
 
Srength of neodymium super magnets Magnetic Materials Philippines
 
Flashlight switch configuration DC Circuits USA
 
What is happening with telekinesis? Force USA
 
Forgets Physics concepts in job interviews General India
 
Explain how a spark jumps from a finger Static Electricity Sparks Namibia
 
Will DC current shock you in water? DC USA
 
Why is the sky blue? Visible Light Nigeria
 
Compare the speed of electromagnetic waves Electromagnetic Waves UK
 
Musical sounds in the environment Sounds with Musical Instruments USA
 

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First 15 letters


AC

Ways to improve site

May 5, 2016

Question

It's better if you could index the questions you receive cause they are very nice and seen some using the blog link.It helps users to get around different types of questions of their favourite subjects like given here:http://www.madsci.org/MS_search.html.

Also I have noticed that while searching for Electricity Generation I could see a page in the search but couldn't see any link in the website that tells about electricity generation.

Justin - USA (26981)

Answer

I'm trying to have a better organization of Feedback Questions. Right now, all the feedback on Electricity are lumped together. I want to get the feedback per subject.

Using our search box at the top of the pages, I search "Electricity Generation". The first entry was "Generating Electrical Current" on the site. Perhaps you missed it.

Anyway, thanks for your feedback and suggestions that will help improve the site.

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General

Why is a meat baked in a gas stove?

May 3, 2016

Question

why is a meat baked in a gas stove

alexander - Belize (26975)

Answer

A gas stove is very effective in heating food. However, an electric stove could also be used.

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Friction

Coefficient of friction on an incline

April 24, 2016

Question

A wooden block of mass 8 kg slides down an inclined plane of inclination 30 degree to the horizontal with constant acceleration 0.4 metre per second square. The force of friction between the block and inclined plane is?

Pratiti - India (26961)

Answer

See Kinetic Friction on an Inclined Surface. It provides the equations needed to solve your problem.

I hope that helps.

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Sounds with Musical Instruments

Uses of harps in physics study

April 21, 2016

Question

what are the uses and application of harps in physics

OPITO - Uganda (26954)

Answer

Harps can be used to study how vibrating a wire can create a sound and musical note. You can show how different thicknesses of wire create different musical sounds. You can also show how tightening the wire changes the sound.

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Causes of Static Electricity

Why would plastic cause static electricity?

April 20, 2016

Question

At work I was vacuuming dust off pieces of plywood with a shop vac. I was getting some pretty good zaps before I had enough. I taped a wire near the bottom of the plastic hose and put a copper squeeze clamp on the other end and put on the pallet rack. Obviously this worked and eliminated the very unpleasant snappage. My question is, what in the world caused this??? Plastic and wood are good insulators of course and this has not only me but maintenance personnel baffled as well. The lights?

David - USA (26951)

Answer

Static electricity is the collection of electrical charges on the surface of the material. This works best on an insulator. A material that conducts electricity, like a copper wire, will allow the charges to pass through it. It helped drain off the charges from the plastic hose.

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X-rays

How do x-ray machines improve security?

April 17, 2016

Question

how do x-ray machines improve the security in our society? and could you explain how.

thanks!

Irraj - Canada (26941)

Answer

X-ray machines are used in airports and public buildings to screen luggage and packages and make sure there are no guns or other weapons hidden inside. The view of the item will show an outline of the gun, since the x-rays don't go through the metal easily.

In this way, troublemakers can be stopped before entering. This improves the security. But note that other devices must be used to detect some explosives that don't show up with an x-ray.

See X-rays and Need for Security for more information.

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Magnetic Materials

Srength of neodymium super magnets

April 15, 2016

Question

I have 3 pcs N52 neodymium super magnets. How do I know the strength of attraction between the two of them in contact with each other without anything in between, or conversely how strong they will push each other apart it they measure 10 mm x 5 mm x 2 mm, with the poles on the larger faces (5 x 10) and, if the poles are on the smaller faces (5 x 2)?

Junnel - Philippines (26934)

Answer

Since there is a wide variation on the strength of neodymium super magnets, the best way to find the strength of attraction and repulsion would be to experimentally measure it. For example, you could use a spring scale to measure the force required to pull the two magnets apart.

Other than that, I don't readily know of equations to allow you to predict the forces.

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DC Circuits

Flashlight switch configuration

April 14, 2016

Question

In your "simple circuit" diagram, you place the "on-off" switch between the negative (-) battery terminal and the bulb. Is this the preferred arrangement ? thanks,

Paul - USA (26932)

Answer

Typically in a flashlight, the bulb is near the positive (+) terminal of the battery, and the on-off switch is on the side connecting the negative (-) battery terminal with the bulb.

You can change the configuration, and it will still work.

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Force

What is happening with telekinesis?

April 14, 2016

Question

Telekinesis. I have learned how to do this. It simply requires the transfer of energy between me and some stones. NO iron involved, by the way.

I'm looking for an opinion as to what is happening.

Derek - USA (26933)

Answer

Although most scientists dispute the possibility of telekinesis because only a few people seem able to do it, there still are others who claim the ability is real. But I keep an open mind about it.

One explanation may be that it is a form of Mysterious Force at a Distance. For example, gravity and magnetism act at a distance with no physical contact. Mental powers may also be able to act in a similar manner.

I know there are a number of websites dedicated to telekinesis.

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General

Forgets Physics concepts in job interviews

April 12, 2016

Question

dear Sir,
I am M.Phil, Ph.D (pursuing) in Physics. But i am very ashamed on Myself that my Basics & all Physics Concepts are very weak. Whenever I attend Interview for Teaching Job I becomes answerless or confused. Also during Demo or Teaching I forget concepts suddenly. Please help me. I am ready to Study from basics & will do hard work but please do provide me best study material.

Jyoti - India (26925)

Answer

You can go through our Physics lessons on the various subjects. Most are fairly basic.

Much of advanced Physics concerns using mathematical formulas and equations to solve problems and show concepts. You need to show a strong background in the maths.

Since you have gone on teaching job interviews, you should be able to make a list of questions they have asked, as well as to anticipate other questions. Write out the correct answers to those questions. They practice an interview with a friend, who will ask questions on the concepts. Practicing an interview several times will help you avoid forgetting things.

Also, in the interview, you can tell them that you relate to students who have problems understanding Physics. This will help you teach them.

Review all your notes from previous classes, as well as your homework.

I hope these ideas help in getting your PhD and in getting a teaching job. Best wishes for your success.

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Static Electricity Sparks

Explain how a spark jumps from a finger

April 9, 2016

Question

Explain the spark jumps from a finger to a metal object when the air is dry

Sylvia - Namibia (26919)

Answer

A static electric spark will jump from one material to another when the difference in the amount of positive (+) and negative (?) charges is sufficient to cause electrons to overcome the resistance of the air gap between the two materials. The electrons heat the air for a fraction of a second, causing the spark and zapping sound.

This works better with a metal object that will quickly conduct the electrons. Also, in dry air there is much less resistance to the spark that in humid air.

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DC

Will DC current shock you in water?

April 9, 2016

Question

will dc current shock you in water?

jerry - USA (26920)

Answer

If you are connected to one terminal of DC electricity, and the other terminal is in the water, then it is possible to get a shock, provided the voltage is high enough. Also, if the water has some minerals dissolved in it, DC or AC electricity can flow better.

I've gotten a nasty shock from touching both terminals of a 90 volt DC battery. The same could occur in water.

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Visible Light

Why is the sky blue?

April 8, 2016

Question

Why is the sky blue?

Ijwo - Nigeria (26913)

Answer

The sky is blue because molecules in the air scatter blue light from the sun more than they scatter the other colors. When you look towards the sun at sunset, you see red and orange colors, because the blue light has been scattered away from the line of sight.

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Electromagnetic Waves

Compare the speed of electromagnetic waves

April 7, 2016

Question

i have a question that came up in my revision....i was asked to.....

compare the speed of electromagnetic waves with each other in space

thanks very much :)

tj - UK (26912)

Answer

The speed of electromagnetic waves varies with wavelength in different materials. See Dispersion of Light for an example with light waves.

However, in outer space, all electromagnetic waves travel at the same speed, which is "c" or the speed of light.

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Sounds with Musical Instruments

Musical sounds in the environment

April 6, 2016

Question

Use different sounds in the environment to produce music

b - USA (26909)

Answer

I've heard recordings of different sounds in the environment, such as sound from a flowing stream, crickets chirping, wind blowing, etc. Those sounds were then edited to make them into a "song" or a form of music.

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Next 15 letters


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