Each day readers send in questions and feedback concerning the various lessons in the School for Champions website. A total of 15906 letters have been answered. They are listed according to date.
You can read them to further your understanding of the subjects.
|Why does Newton's Cradle stop?||Motion||Nigeria|
|Thanks for the derivation||Thanks||Waves||South Africa|
|Lifespan of a sloth||Animal Health||USA|
|Boys don't feel force between them||Gravitation||India|
|Wants to perform Cavendish experiment||Gravitation||USA|
|Correcting units for weight||Gravity||Canada|
|Using sentence from page||Gravitation||UK|
|Venetian blind keeps swinging||Motion||USA|
|Did the Earth exist before Genesis 1 in the Bible?||Religion||South Africa|
|Want a job with Google or Facebook||Career||India|
|How does Physical Science apply to life?||Physics||South Africa|
|CO2 and photosynthesis experiement||Experiments||Uganda|
|Static and hair project||Static Electricity||USA|
|Combining leather and polyester.||Physics||Static Electricity||The Netherlands|
Why does Newton's Cradle stop?
February 19, 2018
why is it that the motion of newtons ball stop and many website name it as perpetual motion ball. and can this motion of the ball made to continue.
GODWIN - Nigeria (28444)
Perpetual motion means that the object moves forever, because there is no loss in energy. However, there is loss due to air resistance and loss due to the collisions of the balls in Newton's Cradle. Thus it slows and soon stops its motion.
Thanks for the derivation
February 19, 2018
Thanks - the derivation for velocity of moving target measured from stationary source using ultrasound was just what I needed.
Neil - South Africa (28445)
I am glad that the materiel was useful to you.
Best wishes for success in your endeavors.
Lifespan of a sloth
February 19, 2018
How old are sloth in human Years?
Rai - USA (28446)
Sloths live between 25 and 30 years. That means that each sloth year equals 3 human years.
Boys don't feel force between them
February 18, 2018
two boys of mass 40 kg and 45 respectively and their distance is 2 metres but they do not feel any force between them .why
TIRTHANKAR - India (28441)
Although there is a force between them, that force is extremely small because both masses are small. Consider the effect of the mass of the Earth on a boy to see how huge at least one mass must be to be felt.
February 15, 2018
calculate the gravitational force between 8000kg and
50,000kg masses which are at 10m a part from each other?
- Nepal (28429)
Apply the equation F = GMm/R^2, where G = 6.674*10^?11 N-m^2/kg^2.
You should be able to do the calculations yourself by substituting the numbers into the equation.
Wants to perform Cavendish experiment
February 13, 2018
I just purchased your Gravity book and look forward to reading it. I am a retired NASA engineer and I want to do the Cavendish experiment for myself. I have made inquiry to Lambda Scientific for their apparatus http://lambdasys.com/products/detail/17 Are you familiar with this, or can you refer me to other apparatuses that are available?
Mark - USA (28426)
I am sure it would be interesting to perform the Cavendish experiment yourself. I'm not sure what their price is, but looking at other similar products, it could be expensive:
Frey Scientific sells a similar device, but the cost is $1120.
PASCO Scientific sells their's for $2300.
It might be worthwhile checking the Physics department of a nearby college or university to see if they have a Cavendish Balance that you might be able to use in their lab. Or perhaps a Physics professor could point you in the right direction.
Best wishes on getting the equipment and performing the experiment.
Let me know how things turn out.
Correcting units for weight
February 5, 2018
Hi, Very good article. I understand that mass is defined as being the amount of matter and weight is the force of gravity on a mass, but just before the summary, you are saying "if you weight 60 Kg (132 pounds) on the earth.... shouldn't it read 588 Newton since you are referring to weight? Or does it refer to Kg force? If so, should it read 588 Kg force since it's multiplied by the force of gravity "a"? Thank you!
Hubert - Canada (28417)
Thanks for pointing that out to me. I updated the page and changed the 60 Kg to 60 N. I should have been more careful. Also see Confusion about Mass and Weight Units for a better explanation.
Using sentence from page
February 3, 2018
Hi, is it ok to copy theee words?
'After the Big Bang, gravitation influenced the formation of the galaxies, stars and planets within the Universe'
I'm writing about the big bang and need this sentence.
Muhammad - UK (28416)
Yes, you can use that sentence. If you are able to, it would be nice to cite the link to our web page.
Best wishes for success in your essay.
Venetian blind keeps swinging
February 3, 2018
I feel silly for asking, but my Venetian blind has been swinging for almost 16 hours. Uh, pendulum? https://www.facebook.com/renejonesnorton/videos/2045769342116603/
Rene - USA (28415)
We also have vertical Venetian blinds that occasionally swing like that due to a heater vent on the floor nearby. But it only moves when the furnace is on.
It seems strange that only the end blind seems to be moving. There could be a draft from the sliding door or some other source of airflow in your room.
You could do some experimenting and hold a tissue and move it around the area to try to find the source of the airflow.
Let me know if you can solve this puzzle.
Did the Earth exist before Genesis 1 in the Bible?
February 1, 2018
Did the earth existed before Genesis 1 and was there a world before Genesis 1 Some believe it was where the dinosaurs came from.
Henrico - South Africa (28413)
The article Big Bang Theory and Religion gives a good explanation relating to the views of various religions on this issue.
I hope that helps answer your question.
Want a job with Google or Facebook
January 30, 2018
sir, i am a 11th class student from india .what should i do for becoming an software engineer at top it compneies like google and facebook.
yogesh - India (28410)
It is good to have a dream of becoming a software engineer with companies such as Google and Facebook.
You can get information from Google Jobs and Facebook Careers.
However, it is best to start near home, perhaps getting an apprenticeship with an IT company in your community. You really need some good experience before getting hired with a major company.
Best wishes for success in achieving your goals. I am sure you will do well.
How does Physical Science apply to life?
January 29, 2018
How to really understand physical sciences and adapt to it in everyday life
Thapelo - South Africa (28408)
Physical Science includes Chemistry, where you can see how materials combine. It also includes Physics, where you can see how energy affect things and causes motion.
When you understand what causes things, you can then get an idea of how it applies to everyday life. See Physical Science Overview for more information.
Best wishes in your studies.
CO2 and photosynthesis experiement
January 27, 2018
Describe An experiment to demostrate that carbondioxide is necessary during photosynthesis.
Kajingo - Uganda (28406)
See The effect of carbon dioxide on plant growth and Experiment to Show that Carbon Dioxide is Necessary for Photosynthesis.
Best wishes for success in your experiment.
Static and hair project
January 23, 2018
My daughter has a class project on static electricity.
She would like to bring her doll in and create static electricity on her hair.
What materials would she need ?
Kristine - USA (28400)
The problem with using a doll's hair is that it is usually stiff and not the best to show static electricity. A better project would be to show how combing her hair or someone else's can create static electricity.
See: Static Electricity Experiment: Electrical Attraction of a Comb.
Best wishes for success in her project.
Combining leather and polyester.
January 21, 2018
i have a question about static energy. if you combine leather and polyester does static electricity arise?
Greetings from the Netherlands!
floyd - The Netherlands (28395)
See Materials that Cause Static Electricity to see a list of materials. Leather results in more (+) charges while polyester results in more (-) charges, making them a good combination for static electricity.
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