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## Main Question or Discussion Point

Centripetal force, enertia, friction, velocity, and mass; these are the forces I've collected that I need to manipulate to simulate vehicle dynamics. I'm playing around in Adobe Flash working on a vehicle rig for a simple game for self education's sake.

Now I don't know anything about physics. I've got a good imagination and that's about it, so I'd love some help with this.

Firstly, I understand that cetrifugal force does not exist (a fictional-force). A person turning sharply in a car may feel pulled to the outside of the curve, but it's an illusion. The car's mass/enertia is trying to go straight while the friction of the 'tangetal' tires are 'generating a cetripetal force' great enough to overcome the car's 'momentum'.

Do I have that right? (?1)

All that's easy and can be simulated without aby serious math: go, stop, turn. But when the centripetal force isn't enough to overcome the enertia, very complicated, interesting, and fun things begin to happen. Either the front, or rear axel-set (simplified from individual tires) looses large amounts of traction (friction) and the car spins and/or slides. The behavior of the spin/slide is dictated by the 'momentum', velocity, and varying amounts of 'friction' and vectors at the front and rear ends.

I've started this project with simplicity in mind. Build a car out of 2 pieces, front and rear axel sets. Each part carries half of the vehicles mass. The rear aims for the front, while the front can be steered in a tangent from the rear's direction and travels independantly in that direction. Measure the

To measure the centrifugal force, I have two ideas. One is to apply a formula; F=mV2/r (mass*velocity squared/radius), but I don't quite udnerstand it. The other is to simulate two instances of the axel sets, one turning and one going straight. Measure the distance between the trurning axel and the continuing axel and use that as a measure for the amount of force pulling the axel out of the turn. When the distance is large enough, traction is lost and the axel travels in a straight line. (?2)

So far I don't know what happens next. When the rear spins out, it should pull the front end, adding to the amount of force that the front-axel centripital force has to overcome, but it isn't adding to the enertia. I don't know what that force is? And if that isn't terribly important, the front will HAVE TO pull on the rear. When a car 'drifts' (big, fast donut) the rear is sliding but it isn't going in a straight line because it's teathered to the front axel which is still turning. I'm not sure yet how to teather it. (?3 and ?4)

About F=mV2/r. I tried this formula where m=100,V=10, and r = 2 and the resulting F equaled 5000. 5000 what? What units are being used here? V in mph? r in feet? I don't even know what unit mass uses, pounds? And 'F' I assume is for Force, newtons?(?5) I also don't know how to find the radius of a fluctuating arc. How do you calculate the radius of any given section of any given curve in a country road?(?6)

I'm beginning to think that simple just isn't going to cut it. Complicated means assigning a mass to the axel sets, calculating their momentum at every frame, calculating the friction of the tires (grip? What unit does friction use? Is it per square inch?), calculating the centripetal force generated and finally comparing it to the centrital force required. Possible, and maybe not so complex. What's your opinion?(?7)

Now I don't know anything about physics. I've got a good imagination and that's about it, so I'd love some help with this.

Firstly, I understand that cetrifugal force does not exist (a fictional-force). A person turning sharply in a car may feel pulled to the outside of the curve, but it's an illusion. The car's mass/enertia is trying to go straight while the friction of the 'tangetal' tires are 'generating a cetripetal force' great enough to overcome the car's 'momentum'.

Do I have that right? (?1)

All that's easy and can be simulated without aby serious math: go, stop, turn. But when the centripetal force isn't enough to overcome the enertia, very complicated, interesting, and fun things begin to happen. Either the front, or rear axel-set (simplified from individual tires) looses large amounts of traction (friction) and the car spins and/or slides. The behavior of the spin/slide is dictated by the 'momentum', velocity, and varying amounts of 'friction' and vectors at the front and rear ends.

I've started this project with simplicity in mind. Build a car out of 2 pieces, front and rear axel sets. Each part carries half of the vehicles mass. The rear aims for the front, while the front can be steered in a tangent from the rear's direction and travels independantly in that direction. Measure the

*centrifugal*force pulling the front and rear to the outside of the turn. If the pulling force is greater than the pre-assigned traction value, the component begins travelling in biased majorly in*a straight line*(?). If the front is subject, then the rig under-steers (slides straight), if the rear is subect then the car over-steers (spins out). Simple enough...To measure the centrifugal force, I have two ideas. One is to apply a formula; F=mV2/r (mass*velocity squared/radius), but I don't quite udnerstand it. The other is to simulate two instances of the axel sets, one turning and one going straight. Measure the distance between the trurning axel and the continuing axel and use that as a measure for the amount of force pulling the axel out of the turn. When the distance is large enough, traction is lost and the axel travels in a straight line. (?2)

So far I don't know what happens next. When the rear spins out, it should pull the front end, adding to the amount of force that the front-axel centripital force has to overcome, but it isn't adding to the enertia. I don't know what that force is? And if that isn't terribly important, the front will HAVE TO pull on the rear. When a car 'drifts' (big, fast donut) the rear is sliding but it isn't going in a straight line because it's teathered to the front axel which is still turning. I'm not sure yet how to teather it. (?3 and ?4)

About F=mV2/r. I tried this formula where m=100,V=10, and r = 2 and the resulting F equaled 5000. 5000 what? What units are being used here? V in mph? r in feet? I don't even know what unit mass uses, pounds? And 'F' I assume is for Force, newtons?(?5) I also don't know how to find the radius of a fluctuating arc. How do you calculate the radius of any given section of any given curve in a country road?(?6)

I'm beginning to think that simple just isn't going to cut it. Complicated means assigning a mass to the axel sets, calculating their momentum at every frame, calculating the friction of the tires (grip? What unit does friction use? Is it per square inch?), calculating the centripetal force generated and finally comparing it to the centrital force required. Possible, and maybe not so complex. What's your opinion?(?7)

**So that's a huge post, with too many questions, so a recap:**

1: Do I understand the concepts of fictional forces, friction, tangents, etc?

2:Any opinions about comparing a 'veering' mass to a 'straight line' mass to find a rough centifugal value?

3ow do the laws of physics explain how things are attached to eachother? Is it measured or calculated? It seems like a product of molecular friction to me. Does it change?

4:What force pulls the rear wheels into an arc? It's teathered to the front axel, but how is that explained with math?

5:What units are used in F=mV2/r? Is this the correct equation to use?

6ow do you claculate a fluctuating arc's radius? Do arcs have radii?

7:If your familiar with coding and programming efficiency, do you have a preference between simulating the physics or aproximating them with shortcuts?

Any help with any questions will be welcome, thanks in advance.1: Do I understand the concepts of fictional forces, friction, tangents, etc?

2:Any opinions about comparing a 'veering' mass to a 'straight line' mass to find a rough centifugal value?

3ow do the laws of physics explain how things are attached to eachother? Is it measured or calculated? It seems like a product of molecular friction to me. Does it change?

4:What force pulls the rear wheels into an arc? It's teathered to the front axel, but how is that explained with math?

5:What units are used in F=mV2/r? Is this the correct equation to use?

6ow do you claculate a fluctuating arc's radius? Do arcs have radii?

7:If your familiar with coding and programming efficiency, do you have a preference between simulating the physics or aproximating them with shortcuts?

Any help with any questions will be welcome, thanks in advance.