# Feedback Blog

Each day readers send in questions and feedback concerning the various lessons in the School for Champions website. A total of 15894 letters have been answered. They are listed according to date.

## List of next 15 letters

### Country

Is sound bent toward the ground? Sound UK

Solenoid and electromagnet Physics Magnetism India

Give examples of using force Physics Force Malaysia

Alzheimer's resource Aging USA

Using adapter between plugs Physics Electricity New Zealand

Why is there a gap in a sound wave? Waves India

Can noise cancellation stop tinnitus? Sound UK

Can a person mess with your 6th sense? Senses USA

Why does an apple change color when cut open? Chemistry India

Voltage for vacuum pump Electricity New Zealand

Seeking permission to use image Magnetism Singapore

Getting rid of chronic pain Religion Buddhism Canada

I would like to cancel a transaction Finances UK

How fast is a magnetic impulse? Physics USA

Next 15 letters

First 15 letters

## Is sound bent toward the ground?

June 15, 2017

### Question

A simple question that I assume has a simple answer. I have assumed that noise travels in all directions from the source of the noise. Does it go in a straight line assuming no distortion by wind? So if noise from a road is reflected and absorbed by a sound barrier the direct undiluted transmission noise will be reduced. Assuming the above is correct, my question is will noise passing over a noise barrier just exhaust itself and not return to land or will it be forced down to the ground and house level by any force other than wind? What type of distance will be involved and will the situation be exactly the same with or without a sound barrier added close to the source of the road noise, please? Many thanks.

ROBERT - UK (28094)

Some of the noise from a road that passes over a wall or noise barrier can be redirected toward the ground due to diffraction of the sound at the edge of the barrier. See Diffraction Affects Blocking Noise.

The amount of the diffraction or bending is a function of the frequency of the sound. I'm sorry, but I don't have the calculations for determining the distances or bending of the waves.

June 13, 2017

### Question

I follow you calculations up until the last part when you multiply the 6.28 * Square root of (0.2). I suspect it has something to do with the /sec/sec. could you explain a little further? Thanks for you time in this matter.

Jim - USA (28090)

The calculations go: 2 * 3.14 * ?(2/9.8) = 6.28 * ?(0.2) = 6.28 * 0.45 = 2.8 sec.

Since 2/9.8 = 0.204, I rounded it off to be 0.2. Since this caused some confusion, I updated the page to show 0.204 and changed 0.45 to 0.4517. The answer is 2.837 or rounded off to 2.8 sec.

## Solenoid and electromagnet

June 13, 2017

### Question

Why solenoid is used for making electromagnet

Nishant - India (28091)

A solenoid is an electromagnet without the iron core in it. The solenoid can be used to pull a core inside it.

## Give examples of using force

June 12, 2017

### Question

Name one examples when force can stop motion.

Name one examples when force can change the shape and size of an object

Nicholas - Malaysia (28088)

You can push on a rolling cart to stop its motion.

You can compress a foam rubber ball to change its size and shape.

## Alzheimer's resource

June 12, 2017

### Question

My grandmother on my mom's side suffered from dementia in her last few years.

It was extremely hard on my mom, who was the one sibling who lived near enough to take care of her. There were days when she was so sweet and thankful to my mom for loving her and being there for her. Then there were those days when grandma seemed to absolutely hate my mom and not know who she was. Yet my mom was still loving and dedicated, caring for her until she passed.

With that on my mind, I was looking for helpful resources to include in an upcoming roundup on caring for and understanding loved ones with Alzheimer's and other forms of dementia, when I found your resources page. Thank you for your effort in keeping those resources up to date.

Just thought I’d share this in-depth guide to improving safety for loved ones with Alzheimer's or Dementia who are living at home like my grandma did, so you can include it in your page.
How to Make a Home Safe for a Loved One with Alzheimer’s or Dementia
https://www.homesecuritylist.com/alzheimers-dementia-home-safety/

Either way, thank you for your effort in keeping those resources up to date, and for supporting my goal of helping to make home a safer place for our loved ones who suffer from Alzheimer's or dementia.

Yvonne

https://healthhired.co/

Yvonne - USA (28089)

Thanks for the suggested resource. I added it to Healthy Aging Resources.

Best wishes in your efforts to make home safer for loved ones with Alzheimer's.

June 11, 2017

### Question

can I use an appliance from south Korea - 220v in New Zealand 230v ? from your chart it would also appear that the frequency will be different also will this cause problems? thirdly the plug types are different is it ok for an electrician to change the plug from c to l

Tina - New Zealand (28086)

The voltage difference should not affect things. However, a 60Hz appliance might perform slower with 50Hz. If there are timers or clocks involved, it might make a difference. It is good to check with the manufacturer website to see if things would work sufficiently.

An adapter plug could be used if the prongs are different. An electrician should be able to make the proper connections.

Best wishes for successful use of your appliance.

## Why is there a gap in a sound wave?

June 10, 2017

### Question

Why there is an gap between successive compressions and successive rarefactions?

Abhisheka - India (28082)

There is no real gap between compression and rarefaction in sound waves. The wave shape is a continuous sine wave. That means one half of the waveform is compression, followed by an instantaneous change to then become a rarefaction.

## Can noise cancellation stop tinnitus?

June 10, 2017

### Question

I have tinitus but am luky as my mind can cancel it out, BUT many people cannot and it drives them mad
can this technology be used for this

len - UK (28083)

It would be nice if noise cancellation would help out, but unfortunately it only cancels external noises. Tinnitus is the perceptions of sounds in your inner ear. There are some medications that can help. See Tinnitus

## Can a person mess with your 6th sense?

June 10, 2017

### Question

Can A person mess with your six Sense if so how would you act

Michael - USA (28084)

Our definition of the sixth sense is precognition or being able to sense future events. It is different than being able to read or affect minds.

It is difficult or even impossible for others to mess with your senses, except by some trickery. You can usually tell if you are being tricked.

## Why does an apple change color when cut open?

June 9, 2017

### Question

Why apple turns into red colour after cutting into slides?

Apples start to oxidize once they are cut open. That is the reason the colour changes.

## Voltage for vacuum pump

June 7, 2017

### Question

hi, i'm looking to buy a vacuum pump from china rated 220v-50hz.can i use it in new zealand which is 240v-50hz with no problems?it has the same plug connection as nz.
regards
dave

dave - New Zealand (28078)

AC voltages vary by about 10% from the listed value. So using a 220V pump at 240 volts should work fine.

Best wishes with your new pump.

## Seeking permission to use image

June 6, 2017

### Question

To Whom It May Concern,

I am Christine from the Copyright team of Kydon Learning Systems Institute. My team consists of myself as the Learning Designer and Project Manager, Bing Ying.

We are writing on behalf of Dr So Ping Lam from the School of Electrical and Electronic Engineering, in Nanyang Technological University, Singapore, who teaches EE3010, Electrical Devices and Machines.

As the appointed Content Partner, we are responsible for converting the course EE3010, into a blended learning course which video lectures will be produced and uploaded into NTU’s learning portal. The image on "right-hand rule for electric wire" which we are seeking copyright clearance will be used in the video lectures and students’ lesson materials. Proper citation using APA style will be used for each image to acknowledge your work. The blended course will be launched in January 2018. There will be about 150 undergraduate students who will have access to the learning portal to participate in this course.

We are flexible about restrictions regarding modification and use, so feel free to let us know about it.

We look forward to your favourable response in granting us the permission to use the image.

Thank you and hope to hear from you soon.

Yours sincerely,

Christine - Singapore (28076)

You have permission to use the "right-hand rule for electric wire" image in your blended course with no copyright or modification restrictions, as long as it includes the proper citation.

Our website is intended for the advancement of learning and education.

Best wishes for success in your blended learning project.

## Getting rid of chronic pain

June 4, 2017

### Question

Can you please explain what the 8 attitudes or paths really mean? What is meant by right view, right speech, right intention, etc.etc. I would also like to know how cessation of desires would end chronic physical pain.As an example someone who is born with a painful condition who is still too young to have formed any desires or attachments in life?

You can see explanations of the items in Noble Eightfold Path in Buddhism. They provide the recommended attitudes and conduct for a good life.

Desires and attachments in life seem to concern the mental and emotional conditions. For example, a person with chronic pain should not be envious of those without the pain. Some meditation practices can help a person alleviate pain. However, medication practices still are usually required.

Best wishes for both physical and spiritual health.

## I would like to cancel a transaction

June 3, 2017

### Question

i would like to cancel a transaction i made with Newchic

william - UK (28071)

You can check with PayPal UK to see their procedures.

You also should be able to cancel through Newchic online. And finally, you should be able to cancel payment through your credit card company.

Best wishes in cancelling your transaction.

## How fast is a magnetic impulse?

June 3, 2017

### Question

Have the effects of magnetism (attraction-repulsion) ever been quantified into speed? How fast is a magnetic impulse?

James - USA (28072)

Magnetic, electrical, and gravitational impulses all move at the speed of light. Typically, a magnetic disturbance will cause an electrical disturbance, resulting in an electromagnetic wave, which also travels at the speed of light.

## Misc

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