# The Phyics of Motion

Discussion in 'Getting Started' started by kf4jqd, Nov 12, 2006.

1. ### kf4jqdActive Member

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Have you ever watch 2 trains on 2 main lines? You have the power set the same. The gears of the locomotives are the same ratio. The same number of cars with equal wieght. However, the inner one out paces the outter train? Ahh, Issac Newton's law of motion applies. The same as our plants in the solar system. The inner train has a smaller "orbit" The outter train has a larger "orbit". This make the inner train appear to run faster! I found with my N scale train, I have to double the speed of the outter train to keep pace. It's been so long ago since I've had college physic's to figure out why!:curse:

Andy

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Hi Andy,

There is another factor to consider when considering orbital speeds - the mass of the planets (which in the trains you describe is the same). What determines the orbital speed of a planet is the planet's mass and its distance from the sun.sign1
3. ### ThoroughbreedMember

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Ahh but you forgot one important thing, the inner 1 has less distance to cover, hint: your inner radius is smaller, correct?:thumb:
4. ### Herc DriverActive Member

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1. The cost of the engine is directly proportional to the height of the table it will fall off of.

2. If you doubt that engine will stay on the tracks at that speed...you'll be right. (See Law 1 above.)

3. No engine currently in production can move faster than a two year old's hand.

4. Cats and trains do not mix well.

5. You will remember just how long it took to string up all those telephone poles at the very moment your hand catches on a few wires.

6. The cost of the building kit is inversely proportional to how well it turns out.

7. Super glue dries faster when it hits objects you don't want glued.

8. The best looking engine shells will only hold on to the frame so many times, then suddenly one day for no apparent reason - won't. (Again...see Law 1)

9. Whatever you just bought will go on sale at your local hobby store next week.

10. When you finally decide to buy a great looking engine or car, it will no longer be in production and you'll have to wait forever to get it.
5. ### kf4jqdActive Member

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What have I created? A bunch of mad scientist!

Andy sign1
6. ### KCSMember

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Herc, if you add two more to that list you'll have the full 12 days of Christmas covered! LMAO.

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If I may add one more:

11) The longer you spend wiring scenery lights, the more difficult it will be to adjust them to the proper scale brightness.:curse:

So, who's gonna finish this list?
8. ### Herc DriverActive Member

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Whoa MadModeler...I applaud you for even attempting to wire scenery (much less trying to adjust the brightness). Right now my layout is daylight only!

But back to the general physics question...My guess is the inside track is slightly shorter and therefore the inside train should always win the race...Unless one of your kids models like Pugsly on the Addams Family tv show - then the physics question is how to make them arrive at the same point in time and space for maximum impact potential.
9. ### TriplexActive Member

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It's simply a question of distance. If both are set to travel at the same speed, the inner one will do a lap faster. (On a double-track figure-8, they should do it in equal time.) This is not the same as orbits.
A planet's orbital speed is determined only by the Sun's mass and the orbital distance. The outer planet has farther to travel, but it also travels slower. The time it takes for one orbit (the planet's year) is proportional to the 3/2-th power of its distance from the Sun.

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Gravitational attraction is between two bodies (eg., the sun and a planet) and the force each exerts on the other. I did not mention the sun since in our system it's a "given" - it's the same sun for all planets ( and whatever other bodies are wandering within it's gravitational field.). In truth, all the bodies within this system affect each other to a greater or lesser degree-which makes it very difficult to establish interplanetary trajectories. The fact that the folks at NASA, JPL and others can do so is a tribute to their fantastic mathematical ability!!

The 12th maxim...??? Anyone???

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