If you are a student, think of cars in terms of physics (2) [Cornering].

The key to driving fast on metropolitan highways and mountain passes is how well you can attack corners. I will show you how I practised turning corners faster.

centrifugal force

First of all, only attack corners on dry roads. Wet roads have unreadable limits and you can be swept away at a moment's notice.

Force is mass x acceleration. Centrifugal force is also a product of "mass" and "acceleration" in the opposite direction of the bend.

And the acceleration depends on the radius and speed of the curve. Have you ever seen a sign on a motorway that says 'R=300'? That means "This curve has the same curvature as a circle with a radius of 300 m". If the radius of the curve is r [m] and the speed is v [m/s], the acceleration a is as follows.

$$a=\frac{v^2}{r} [m/s^2]$$

Centrifugal forces are "proportional to the square of the velocity" and "inversely proportional to the radius".

For example, if you always turn a certain corner at 50 km/h and the lateral G is 0.2 G, if you double your speed to turn at 100 km/h, the lateral G will quadruple to 0.8 G.

If the lateral G at a certain speed on a curve with a radius of 100 m is 0.6 G, the lateral G on a curve with a radius of 200 m at the same speed is 0.3 G.

Definition of G

There are various Gs, such as "I feel G -", the G that appears on the car locator, or the G that appears in the impact degree setting of the DRA RECO's recording upon impact. The G or g is a certain constant, calculated as "00 x 9.8" as a value that is accurately expressed in physics.

Gravity also works with an acceleration of 1 G in the direction of the ground, which is called gravitational acceleration. This gravitational acceleration is the standard for G. For example, when a lateral G of 1.00 occurs when cornering, it means that a centrifugal force of the same magnitude as gravity has occurred. You would be surprised if a force equal to gravity were generated right beside you when you are driving, wouldn't you? Cornering that generates 1.0 G sideways is that scary.

Knowing and practising G.

The limiting G depends on the tyres you have on and the type of car. I have a car locator with G sensors on my car as shown in the picture below.

IMG_4160 - mbFAST Tuning — Accelerometers for car location.

I don't think you can imagine what it would be like if you didn't have these accelerometers, so I'll give you an example,

Normal brake: 0.1 G to 0.2 G
Poor braking, strong braking: 0.3 G to 0.5 G
Emergency braking, full braking: 0.6 G to 1.0 G or higher.

Gentle curve: 0.1 G to 0.3 G
Slightly sharp turns, sharp steering: 0.4 G to 0.5 G.
Attack on metropolitan highways and mountain passes: 0.6 G or more.
Tyres start to squeal: 0.8 G or more.

Full braking on icy roads: 0.1 G
Full braking on snow: ~0.3 G
Full braking in the wet: 0.6 G to 0.7 G
Full braking on dry roads: late 0.7 G

I have practised by actually driving while looking at the accelerometer, or following a fast car and turning while looking at the accelerometer.

The radius of the curves on the roads you use all the time is naturally not going to change. I have kept in mind that the centrifugal force depends on what km/h I am driving. I thought that where I always turn at 100 km/h is 0.5 G, so if I'm going 110 km/h, it's about 0.6 G. I kept getting closer and closer to the limit.

Cornering practice is easier on motorways, where speed is easier. On a mountain pass or a sharp bend, the lateral Gs are approximately doubled when 50 km/h becomes 70 km/h (1.4 x 1.4), or 1.96 times, whereas on a motorway, when 100 km/h becomes 120 km/h, the lateral Gs are only 1.44 times higher. The same doubling only occurs when turning at 200 km/h.

It is dangerous because if you are turning at the limit on a mountain pass and go even a little bit over the limit, you will lose grip immediately, whereas on a motorway you don't even think about making a noise and the centrifugal force is not that strong even if your speed is increased by 10 km/h. You just get scared and can't go any further before the tyres become. The margin is also there, so it's fine!

http://mbfasttuning.com/2020/04/24/学生なら物理で車を考える [Cornering section]/