# Science Feedback

by Ron Kurtus

Each day readers send in questions and feedback concerning the various lessons in the School for Champions website. A total of 4977 letters have been answered.

## List of most recent 15 letters

### Country

Water pressure when stones added to a pool Pressure UK

Gas pressure on .5 square inch area Pressure Pakistan

Animal and plant groups General USA

Applying a torque Force and Torque Myanmar

Why does light change its speed? Refraction of Light Pakistan

Define refraction Refraction of Light Pakistan

How can we cool the Earth? Heat Transfer on Earth USA

Why does light separate into colours? Dispersion of Light Pakistan

How is physical science related to geology? General Nigeria

How does a vacuum in a thermos prevent heat transfer? Heat Transfer Tanzania

Need glass that blocks infrared Heating a Greenhouse India

Transverse electromagnetic waves EM Waves Philippines

Definition of force at a distance Force at Distance USA

Can understand maths but not science General SA

Atmospheric insulation Heat Transfer on Earth Nigeria

Next 15 letters

## Water pressure when stones added to a pool

February 9, 2017

### Question

Ron, Thanks for your article. what happens to water pressure if some of the water is removed and replaced by stones. In a pool. I think the water pressure at bottom of pool is reduced.

Kieran - UK (27870)

Water pressure is caused by the weight of the water above the point of measurement. If the pressure is measured in grams per square cm, it would be the weight of the column of water 1 square cm times the height.

This would be true for water pressure at the top of the stones. Since the distance to the surface is reduced, the water pressure would be less at that point than at the bottom with no stones.

## Gas pressure on .5 square inch area

January 13, 2017

### Question

what will the gas pressure on .5 square inch area if the pressure is 10 psi in a container of gas.

asif - Pakistan (27801)

"psi" stands for "pound per square inch". If the area is 0.5 square inch, the pressure would be 5 pounds.

## Animal and plant groups

January 4, 2017

### Question

1. 10 animal groups
2. 10 plant groups

Jesus Ramon Neopolo - USA (27783)

See Animal Groups and Plant Groups for information.

## Applying a torque

November 7, 2016

### Question

Hi,i'm a student sir.
I want to know, what can we do if we know the torque?

Zarni - Myanmar (27475)

Torque is the rotational force on a shaft. This can be used to turn a wheel or other object or simple machine. If you know the torque being applied, you can calculate how well the force is applied.

## Why does light change its speed?

November 6, 2016

### Question

Why When light passes from one transparent medium to another it changes its speed and direction?

The speed of light is different in different materials. Often it is related to the density of the material. For example, water is more dense than air and thus is slower in water. This is called the index of refraction and is related to bending at an angle.

## Define refraction

November 6, 2016

### Question

Can I define refraction

Refraction of light is when it bends when going from one transparent material to another at an angle. When light goes from air to glass at an angle, it bends or refracts.

## How can we cool the Earth?

October 27, 2016

### Question

So how can we humans get rid of heat on our planet and cool the earth?

David - USA (27420)

There really isn't a way for us to cool the Earth, but humans can prevent or slow down global warming, which is caused by the "greenhouse effect" of excess carbon dioxide in the atmosphere.

See Infrared, Gases and the Greenhouse Effect and Heating a Greenhouse for some explanations.

Eliminating burning of carbon-based products would help a lot. However, it is almost impossible to get people to stop using their gasoline-powered automobiles and other such items.

## Why does light separate into colours?

October 3, 2016

### Question

Q1 . why white light changes into different light Q1, whith outuse of prism why white light looks white ?and use of prism why white light distrtibute in different colours of light?

hasher - Pakistan (27342)

The light you see--like from a light bulb--actually consists of all of the colours in the spectrum, but it appears white because your eyes average out all the colours.

But one characteristic of light waves is that the different colours or wavelengths travel at different speeds when moving through glass. For example, red light travels faster in glass than green light, and green light travels faster than blue light. Thus, in a glass prism, the colours separate according to their speed through the glass.

## How is physical science related to geology?

July 28, 2016

### Question

What are the aspect of physical science related to geology and what are the hints in study physical science

Effiong - Nigeria (27176)

Physical Science concerns the various sciences that are not related to life. Geology is the study of solid Earth, the rocks of which it is composed, and the processes by which they change. It is sort of the history of the Earth.

A good resource is at Geology.com, which gives information on many aspects of the science.

Best wishes for success in your studies.

## How does a vacuum in a thermos prevent heat transfer?

July 19, 2016

### Question

Please l need some clarification on
vaccum in themos prevent heat transfer by which way

peter - Tanzania (27155)

Much of heat or thermal energy is transferred through the vibration of high energy molecules affecting low energy molecules. In other words they heat up the molecules.

But if there is a vacuum, there are no molecules to heat up. The vacuum acts to block the heat transfer.

However, some heat transfer comes from infrared radiation. That is why a thermos usually has a shiny interior, in order to reflect the radiation and eliminate the heat transfer.

## Need glass that blocks infrared

July 17, 2016

### Question

Hi..
I'm working on project on solar distillator. So I need a glass which transmits the solar radiation into the box, but blocks the infrared to escape out. Do you have any idea about that glass or coatings..?!

Hemant - India (27153)

Standard window pane glass will work fine. For a background on different materials, see Best Materials for a Greenhouse Roof.

Best wishes for success in your project.

## Transverse electromagnetic waves

July 3, 2016

### Question

is transverse wave and transverse electromagnetic wave the same? if not what is a transverse electromagnetic wave? how can you describe it.

fritzie - Philippines (27117)

The wave motion of an electromagnetic wave is transverse. It is similar to wave motion you can create with a rope, except that the EM wave is in three-dimensions. There are other examples of transverse waves in Overview of Wave Motion.

I hope that helps. Best wishes on your studies.

## Definition of force at a distance

June 18, 2016

### Question

definition of force at a distance?

- USA (27090)

Most forces require direct contact, but there are some forces that act when the object are separated--even at great distances. A good example is gravitation, where there is a pull from very great distances. Magnetism is also a force at a distance, since the magnets act on each other when separated.

## Can understand maths but not science

June 16, 2016

### Question

Good day
I would be happy to know what makes me to understand maths clearly and not to understand physical science concepts? well I do not understand anything since the beginning of the year of my grade 12 but now I would love to change and I'm asking for help so I can make it this year with distinctions in this subject.

kgomotso - SA (27084)

Mathematics is fairly abstract. so you must have more ability in dealing with numbers and abstract concepts.

On other other hand, Physical Science primarily concerns real objects and their properties. Observation of objects around you and how they behave under different circumstances is valuable in understanding the various science concepts.

Advanced Physical Science starts becoming more and more mathematical, where formulas and equations are used to describe and predict how object behave. If you are good in the maths, you should have an advantage on others in Physical Science.

I hope that helps. Best wishes in excelling in Physical Science. I am sure you will.

## Atmospheric insulation

June 5, 2016

### Question

discuss insulation loss in atmosphere

Tarfena - Nigeria (27057)

Insulation refers to a material that prevents the loss of heat. The atmosphere acts as an insulator to prevent heat loss from the Earth into space. The main way is that the atmosphere absorbs much of the infrared rays going out from the Earth.

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