# 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.

## List of next 15 letters

### Country

Project on changing phases or state of matter Changing States of Matter USA

Someone yelling at 70 db Sound and Obstacles USA

AC and DC electricity AC Oman

Neighbor is transmitting high frequency sounds Sound Frequencies and Wavelengths USA

Consequences of heat transfer Heat Transfer on Earth Tanzania

Projection at a 45 degree angle Velocity Equations for Objects Projected Upward USA

Speed on Earth and on the Moon Mass and Weight Pakistan

Must insulate a room Thermal Insulation Pakistan

Acceleration does not seem right Displacement Equations for Falling Objects USA

Electron donor and electron acceptor Physics - Detection of Static Electricity Nigeria

Frequency of sparks jumping gap Static Electricity Sparks USA

Light rays focused with mirrors Optical Devices Pakistan

Why do opposite poles of a magnet attract? Basics of Magnetism Ethiopia

Joke on average speed Kinematics USA

Ceiling fan kicks off circuit breaker Electrical Power USA

Next 15 letters

First 15 letters

## Project on changing phases or state of matter

November 24, 2015

### Question

Dear School for Champions,

We are students from ZWMS in Indiana. We're doing a project on why some substances skip a phase change. We were wondering if you could give us some pointers?
Thank you for your time and consideration!

Sincerely, Talli and Eleanor

Talli - USA (26560)

The change in phase of state of matter is affected by temperature and pressure, as well as the molecular structure of the material. See Pressure and States of Matter for a nice illustration of changing phases, including skipping a phase.

I hope that helps. Best wishes for success in your project.

## Someone yelling at 70 db

November 22, 2015

### Question

If someone yelled something at 70 dcb's how much sound will make it through if the house is 100 ft away and to the left of where someone is speaking?

Phillip - USA (26556)

Yelling or very loud talking can create of sound of 70 decibels (db). Under normal conditions, the sound spreads out and decreases with the square of the distance. The sound would decrease even more if you heard it inside a house (unless the windows were open). How much also depends on the structure and insulation of the house.

However, people tend to focus on annoying sounds, making them seem more noticeable and louder than they actually are.

## AC and DC electricity

November 21, 2015

### Question

I want in conclusion Ac and Dc currant

khalid - Oman (26553)

See Direct Current (DC) Electricity and Alternating Current (AC) Electricity for information.

## Neighbor is transmitting high frequency sounds

November 17, 2015

### Question

Please see the phasor painfield generator at www.amazing1.com or information unlimited. The neighbor below is using to harass me-high frequencies. How can I prove this.

Maag.

- USA (26540)

I once had a neighbor who was using a high powered CB band radio that would cause my loudspeakers to transmit his loud conversations, day and night. I mentioned it to him in a friendly manner, and he then toned it down.

What I'm saying is that it might be good to approach your neighbor and ask if he knows anything about some high frequency sounds in the area. Don't accuse, but ask for information and perhaps some help. If you act nice, often people will stop what they are doing.

However, if your neighbor is a complete jerk and is really trying to harass you, at the very least, by talking to him, you can get an idea of what he is doing and why.

If it really seems to be a case of harassment with these sounds, you can then talk to your apartment manager about the situation.

But the first action is to be nice to try to get to the bottom of the issue.

I hope that helps such that the problem will be solved.

## Consequences of heat transfer

November 17, 2015

### Question

Enock - Tanzania (26541)

Much heat is transferred from the Sun's radiation to the Earth. Most of it then re-radiates back into space. However, if greenhouse gases in the atmosphere prevent the heat from sunlight from going back into space, it will result in the air become warmer and having hotter weather. This can affect weather patterns that cause drought.

## Projection at a 45 degree angle

November 17, 2015

### Question

What if you were throwing at a 45 degree angle ? What's equation would be.

See Effect of Gravity on an Artillery Projectile to see the equation at various angles.

## Speed on Earth and on the Moon

November 13, 2015

### Question

if some known force is applied on some known mass.will it move with the same speed on earth as well as on moon?

Mahrooz - Pakistan (26525)

If the force is applied parallel to the surface of the Earth, as well as the Moon, the speed will be the same, since it is independent of the gravity force.

See Horizontal Motion Unaffected by Gravity for information.

## Must insulate a room

November 11, 2015

### Question

my project is to insulate any room to maximize the chiller capacity in the room
i requred all information + mathematically expression expkanation + calculation...(assumed)
last date is 20-11-2015
i shall be very thankfull for this favor....

Muzammil - Pakistan (26516)

Insulating materials often have an R-value, which is measure of thermal resistance used in the building and construction industry. Under uniform conditions it is the ratio of the temperature difference across an insulator and the heat flux (heat transfer per unit area per unit time through it.

You need to determine the internal surface area of the room and the type of insulating material to use. Often a fiberglass or Styrofoam insulation is used, so you need to find the R-value for such material and its thickness.

It would be good to check with companies making coolers for their engineering advice.

I hope this helps. Best wishes for success in your project.

## Acceleration does not seem right

November 11, 2015

### Question

I understand y = gt^/2... and g is the same as (a) for acceleration in F = Ma... thus we can have y = at^/2. And with metric (a) or (g) is 9.8m/s^. ...What if... gravity acceleration were 1 m/s^... and a body of 1kg is dropped from zero to one second elapsed time, and it is displaced 0.5 meter... I assume it reached a velocity of 1 m/s in the one second... then this, describes the newton (N)...as one newton. I don't see how a body of 1kg body mass can be accelerated to an end of acceleration increment (from zero) to 1m/s velocity and be displaced one meter! A v = 1.414, and 1.414 s^,for 2 N... seems like what it would take to get 1kg displacement? (I have looked up and at what they call the newton meter of Pa for a cube of pressure for the continued force and work of 1 joule... but something still seems out of wack? Can you explain it better.
Ron Davis

Ronald A. - USA (26523)

Let's look at simple acceleration and not concerning gravity. Acceleration is the change in velocity over an increment in time. Thus, if the change in velocity is from 0 m/s to 1 m/s in one second, the acceleration is 1 m/s^2.

The distance an accelerating object travels is the average velocity times the time. In this case, the average velocity is 0.5 m/s and thus the distance traveled in one second is 0.5 m.

The force required to accelerate 1 kg, 1 m/s^2 is one newton. F = ma.

I know it seems confusing that the distance is only 0.5 m, but the average velocity is only 0.5 m/s.

## Electron donor and electron acceptor

November 9, 2015

### Question

how do i know which of the following is the electron donor and electron acceptor
1. fountain pen with coat sleeve
2. glass with silk
3. nylon comb through dry hair
4. ebonite rod with fur

chris - Nigeria (26508)

See Effect of Materials on Static Electricity and compare material combinations to see which are electron donors and which are acceptors.

For example, on the list, glass tends to give up electrons and gains positive charges, while silk also gives up some electrons, but not as many as glass. Thus, glass would be the donor.

Ebonite attracts electrons while gives up electrons.

I hope this helps your understanding.

## Frequency of sparks jumping gap

November 9, 2015

### Question

As far as an 'adjustable spark gap' of a brass type with ball ends connected to an electrostatic generator: Does the Spark going across the gap reflect back and forth before going to ground? It looks to me it does. Is the energy across the gap acting like a 'Doppler Effect'? From some of my experiments it seems the spark gap I use at a certain (f freq) gap actually is stronger then if there were no gap and connected straight.
If you could comment on this to me it would be of much help.
Maybe I am delving into the unknown but if this is true to some extent
that would be great for my research. I have no way to measure if a spark gap at a certain freq has more power before its final ground journey. Thanks

Maure - USA (26509)

A spark jumping across a gap is caused by an excess of electrons jumping to an area with less charges. But what can happen is that when the electrons jump the gap and cause a spark, too many jump and cause the other side to have an excess. Since the air is hot and ionized, this excess will jump back in the reverse direction. It could happen several times. This is often seen in lightning strikes.

I'm not sure how to measure the frequency of the sparks going back and forth, but I'm sure there is a method to do that.

I hope that helps. Best wishes in your experiments.

## Light rays focused with mirrors

November 7, 2015

### Question

I've seen in a book written that light rays can be gathered at one place to focus them on a subject by multiplying and reflecting through the mirrors.
But an human eye can't see this process, an electronic pen is used

The human eye uses its lens to focus the image on the retina, the same way as a camera uses a lens to focus on the film or detector. Although the energy is the same when the light is focused, it is concentrated on the image.

There are some cameras and devices that use curved mirrors instead of lenses. Of course, you cannot see what is happening inside the device.

I am not sure what an electronic pen is. However, a detection device can recognize the incoming rays and image.

## Why do opposite poles of a magnet attract?

October 29, 2015

### Question

why opposite poles of a magnet attract and identical poles repel each other?

moges - Ethiopia (26489)

It is a property of magnetic fields and it similar to static electricity where opposite charges attract and like charges repel.

## Joke on average speed

October 25, 2015

### Question

Good Morning,
I am trying to reconstruct an old favorite joke and need some help identifying the person behind the following principle. It takes the distance between 2 fixed points and the time it takes to determine the (average) rate of speed.

Hopefully I have not complicated the question. :) And here is the joke.

Mystery scientist was pulled over on the freeway for speeding. The Trooper approached his car and asked him, "Do have any idea how fast you were going?"

He replied, "No but I know exactly where I was at."

Thanks and haqve a great day, Larry

Larry - USA (26474)

From Wikipedia: The Italian physicist Galileo Galilei is credited with being the first to measure speed by considering the distance covered and the time it takes. Galileo defined speed as the distance covered per unit of time.

I guess you could use Galileo in your joke.

## Ceiling fan kicks off circuit breaker

October 23, 2015

### Question

Hook up a ceiling fan and ran my wire ,to the switch on the wall which is were I get my power .but it keeps kicking off the breaker box

sergio f navarro - USA (26470)

If the circuit breaker keeps kicking off, it could mean a short circuit or that your fan is drawing too much current.

A number of things to consider are: Is the fan the correct type for the power input? Do you have the correct wires connected: hot wire to hot and common to common? Is the grounding connected properly?

I hope that helps getting your fan to work properly.

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