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# Car physics

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Anyone know how to do realistic car movement?

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well..... if you''ve taken high school physics you should have some idea of what goes on. There''s a force driving the car which is equal to its acceleration times it''s mass represented by
F = ma
depending on the condition of the road there is friction going on which opposes the motion of the car which is equal to
Friction = uFn
u ( greek letter mu ) is a pure number. it''s between zero and one, the lower it is, the lower the friction. On a slippery road it would probably be something like .1 ( just a guess, I have no real idea )
Fn is the normal force. The normal force is perpendicular to the forward force of the car, which is also opposite of the weight force ( assuming that the car is level )
so.... Fn = mg
what that means is that the normal force is equal to the mass ( in kilograms ) times the force of gravity ( roughly 9.8 m/s^2 )
so if you have a 10 kilogram car ( not possible I know, but bear with me ) the normal force would be 98 N ( newtons - the standard measurement of force ). Again for the sake of argument let''s assume the friction coefficient is .1 ( slippery road ) hence, the friction is 9.8 N
now.. let''s assume you''re accelerating at 15 m/s with a mass of 10 kg
that''s 150 N of force in one direction being opposed by 9.8 N of friction force in the other, so there is a net force of 140.2 N acting upon the car in the horizontal direction.
Putting on the breaks and such is another matter entirely, one which I don''t want to get into.
If you''re going around a curve things get really hairy with centripital force/acceleration and all that good stuff, and I REALLY don''t feel like going into that.
There are some equations to calculate how long it will take you to slow down and such, however they elude me at the moment. If you do a search for mechanics on the net you should find some good stuff to help you.
All of this needs to be programmed into your game in order to make it realistic.
good luck, it''s not easy to be sure.
-Aztec
Eagles may soar, but weasles don''t get sucked into jet engines.

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Zeddy..

Wander over to my website. I''m currently looking for the time and the motivation to continue coding so if you want to swap any ideas let me know.

Later

Matt

Check out my project at:www.btinternet.com/~Matthew.Bennett

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Zeddy..

Wander over to my website. I''m currently looking for the time and the motivation to continue coding so if you want to swap any ideas let me know.

Later

Matt

Check out my project at:www.btinternet.com/~Matthew.Bennett

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Sorry about that... It kept timing out and I kept re-trying!

Oops

Edited by - 3dModelMan on August 27, 2000 4:28:25 PM

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