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Feedback Comments on Motion

by Ron Kurtus

A total of 228 comments and questions have been sent in. They are listed according to date.

List of next 10 letters




Pendulum What is circular motion? India
Newtons Cradle Describe ways of minimizing noise pollution Philippines
Newtons Cradle Need bibliography material USA
Newtons Cradle Do the balls in the middle also start moving? Qatar
Motion Object reverses direction at constant acceleration Gilgit-Baltistan
Pendulum Equations How do I determine the period of oscillation? Kenya
Motion Laws I need a free book Ghana
Newtons Cradle How fast does the momentum move? USA
Motion I don't understand half the words here Netherlands
Newtons Cradle Pratical uses for conservation of energy? USA

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First 10 letters

What is circular motion?

Topic: Pendulum


February 23, 2011

what is circular motion?

pritish - India



Circular motion is when something travels in a circle. Swinging an object on a string and the orbits of planets are examples of circular motion.

However, the tendency is to go in a straight line.

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Describe ways of minimizing noise pollution

Topic: Newtons Cradle


February 16, 2011

describe ways of minimizing noise pollution in our community.

chadrinka - Philippines



See our lesson on Noise Reduction of Sound

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Need bibliography material

Topic: Newtons Cradle


February 13, 2011

Hello! This website is a big help for my science project that I am woriking on. I want to give you the write recognition for your help. For my bibliograpghy I have to include the first and last name of the website owner, the website title, the date created, the date accessed, and the URL address. (EX: Jones, Jack. Anne Rice. 22 Sept. 2000. 10 Apr. 2002. ) I am contacting you because I do not know how to find this information. Please respond so I can move on with my project.

Thanks, A young scientist

a young - USA



After each article, there is a by-line with the name of the person who wrote the article and should get credit. There is also the date it was written. Information for your reference or citation should be:

Ron Kurtus
30 May 2010
School for Champions

Best wishes for success in your project.

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Do the balls in the middle also start moving?

Topic: Newtons Cradle


February 8, 2011

after sometime, do the balls in the middle also start moving?

ashok - Qatar



If the Newton's Cradle is perfect, only the end balls will move. For example, if you pull two balls, then only two balls on the other end will move.

However, the devices you can buy or make are not perfectly made or aligned. After a while the middle balls start to move too.

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Object reverses direction at constant acceleration

Topic: Motion


February 4, 2011

can an objectb reverse its direction of travel while maitaining a constant acceleration ?if so,given an example.not,provide an explanation.

IJLAL - Gilgit-Baltistan



When you throw a ball up in the air, it is slowing down at a constant acceleration due to gravity until it reaches its peak, when it then reverses directions and starts falling to the ground.

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How do I determine the period of oscillation?

Topic: Pendulum Equations


January 17, 2011

1. I like to know the meaning of oscillation.

2. How do I determine the period of oscillation for a small angle or if angles are not small when I don't know the value of l ( length)

Mary - Kenya



Oscillation means going back-and-forth.

Since the period is dependent on the length of the wire, you really need to know the length to calculate the period. However, you can get values experimentally by measuring the time it takes a pendulum to go back-and-forth several times and then dived by the number of times. For example, measure the time it takes to go back-and-frth 5 times and then divide by 5 to get the period.

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I need a free book

Topic: Motion Laws


December 19, 2010

i need a free book to help me in my studys

bernard - Ghana



You can use our website material to help you study. I'm sorry, but we have no books available.

Best wishes for success in your studies.

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How fast does the momentum move?

Topic: Newtons Cradle


December 13, 2010

How fast does the momentum move through a perfectly linear Newton's Cradle that extends across North America? I don't think it travels at the speed of sound. If you pulled on a string of the same length, would the force or momentum moving through the string that causes the other end of it to move toward you... travel with the same speed that the momentum does through the cradle?

William - USA



Usually, the balls in a Newton's Cradle are made of steel. When the first ball hits the second, it sends a compression shock wave through the ball, due to the slight elasticity of each ball. This shock wave travels at approximately the speed of sound in steel, which is 6100 m/s or 20,000 ft/s. The shock wave transfers the momentum to the next ball and so on.

Now, if this was a large series of balls, you would have to take into account the various damping effects and losses due to heat and such. Still, using the speed of sound in steel is a good estimate.

A good experiment is to measure how fast the impulse goes from the first to the last ball.

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I don't understand half the words here

Topic: Motion


December 5, 2010

i'm only 10 and i dont understand half the word here could you make them easier for me?? i desperatly need help in motion and acceleration but i cant understand it :(

- Netherlands



It can be difficult to understand some of the words in the lessons, especially if English is not your main language. I've tried to make the language as simple as possible and yet be able to explain the material.

Some of the lessons include audio, where you can hear the words spoken. That may help you.

If you are having trouble understanding certain words, you can look up the definition on Google or other search engine. But that may your studying.

Try the best you can, and will also try to make the words more simple. Best wishes and learning the lessons.

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Pratical uses for conservation of energy?

Topic: Newtons Cradle


October 22, 2010

What else is this principal used for? Other partical uses for this info on conservation of energy>

Karen - USA



Newton's Cradle is a demonstration of the conservation of energy and momentum. The principles can be used to determine velocities and directions in collisions.

In Physics, it is used in the study of interactions and collisions of atoms and molecules. Any time two objects collide, you can get information on the resulting motion. This could be after a car accident or studying how far a ball will go when someone kicks it.

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