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Physics/Train Derailment Example.

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Question
Dear Prof Steve

http://en.wikipedia.org/wiki/Newton's_laws_of_motion
http://teachertech.rice.edu/Participants/louviere/Newton/‎
http://en.wikipedia.org/wiki/Momentum‎
http://www.stmary.ws/highschool/physics/home/notes/dynamics/momentum/LAWCONSERVA

Example : Rocket launching is example of Sir Issac Newton's
Third Law of Motion.


Examples :

1. Train running at 300 km/hr speed may get derailed by applying Sudden Brakes manually by motorman or automated.

2. Automobile viz Car, Truck etc is moving at 150 km/hr speed. Human Beings sitting in the automobile experience a forward push when sudden brakes are applied by the driver.

i.e. Body having mass moving at maximum speed is suddenly brought
to rest by applying resist force (apply brakes).

The above two examples best illustrates which Sir Issac Newton's three Laws of motion, Law of conservation of momentum etc ?.

Awaiting your reply,

Thanks & Regards,
Prashant S Akerkar

Answer
The first one is an example of instability through bad engineering.  Derailment isn't really an example of Newton's laws.  The second one would be an example if it were correctly phrased.  The passengers experience a backwards push against their momentum, not a forward push when brakes are applied.

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Dr. Stephen O. Nelson

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I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.

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I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

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Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

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