# Car Tutorial Guide (Unity3d): Exploring an Alternative Physical Model (Part 2 of 3)

• Tutorial
Before we begin, I want to warn you that this is not a translation of the official manual, but my personal study of alternative physics in a car from the Car Tutorial manual.

Part 1
Part 2
Part 3

### The study of an alternative physical model:

Part 1
Part 3

P.S This article contains the main examples, in the video there are one and a half times more so that anyone interested in each of these examples, watch the video:

In this section we will study the mass of the car and the effects of the location of the center of gravity in our car.

So, as we know from the last article, the mass of our car = 1445kg.

Center of gravity (CoG) - placed as follows:

With these characteristics, our car can be safely controlled. During the test, all the settings will be as we set in the previous article. In terms of speed with the characteristics above. we gain 102 km / h in about 6 seconds. that is, our car accelerates very quickly with the settings that we set earlier and with the center of gravity as shown in the picture above.

Let's increase the mass of our object to 5000 kg:

Let's see what happens. We in 10 seconds on the same route accelerated only to 89 km / h. After stupidly drove onto the slope and the speed naturally fell. That is, with an increase in mass, the Acceleration of our machine fell. Because our car has become heavier.

We will increase the mass of our facility to 10,000 kg.

Let's see what happens. We in 20 seconds on the same route accelerated only to 69 km / h. After stupidly drove onto the slope and the speed naturally fell. That is, with an increase in mass, the “acceleration” of our machine again fell. Because our car has become heavier.

I could not help but notice the “tight” control - the car turned ate. And I didn’t stop on the slope, it rolled back down the slope, there was not enough engine power to accelerate uphill.

From here we now know that to create a truck, an important factor will be the change in body weight, to the real one (like a real car).

With the mass of the car a little figured out now I will present a dozen options for the location of CoG (Center of Mass) on the car. I will evaluate each CoG location on this vehicle in three ways.Speed, stability, controllability . On a scale of 1-5. Change the default weight of the car to 1445 kg.

### 1 Option

Speed ​​- 5;
Sustainability - 4;
Manageability -3;

In principle, a good mb option is a little higher just below, to position the center of mass of the car and the car to lose flaws.
Speed ​​- excellent acceleration, high speed.
Stability - when flying, something bends slightly with his nose, almost turned over from a high mountain, but quickly recovered.
Manageability - lost control at high speed when turning on slopes (skidded).

### Option 2

Speed ​​- 5;
Sustainability - 3;
Manageability -4;

In principle, a good option.
Speed ​​- excellent acceleration, high speed.
Stability - when flying, it’s somehow not clear that from a small hill it flies with its front upright, then from a high mountain its nose dips and turns on its side, with some kind of repulsive defects.
Manageability - management is quite good, only at a high speed it is a little taut.

### 3 Option

Speed ​​- 4;
Sustainability - 3;
Manageability -3;

The option is mediocre.
Speed ​​- acceleration is good, speed is excellent, but on slopes, acceleration is slower than on a flat road.
Stability - when flying flies with a raised top.
Manageability - control is quite high speed and a bit tight turn and a little drifts.

### 4 Option

Speed ​​- 4;
Sustainability - 3;
Manageability -3;

The option is mediocre.
Speed ​​- good acceleration, excellent speed. But on the slopes, acceleration is slower than on a flat road.
Stability - when flying flies with a raised top.
Manageability - control is quite high speed and a bit tight turn and a little drifts.

### 5 Option

Speed ​​- 5;
Sustainability - 5;
Manageability - 2;

Option is not very.
Speed ​​- good acceleration, excellent speed.
Stability - stability is even better than necessary (you need to try to turn the car over).
Manageability - lost control at high speed when cornering on slopes (very heavily skidding on light corners).

### 6 Option

Speed ​​- 5;
Sustainability - 5;
Manageability - 4;

The option is almost excellent, a small shell shock with drifts.
Speed ​​- good acceleration, excellent speed.
Stability - excellent stability.
Handling - small problems with skidding on corners, but in principle for the racing simulator is the most.

### 7 Option

Speed ​​-5;
Sustainability - 2;
Manageability - 4;

Option is not very.
Speed ​​- good acceleration, excellent speed.
Stability - the stability of the machine can easily roll over.
Handling - small problems with skidding on corners.

### 8 Option

Speed ​​- 5;
Sustainability - 2;
Manageability - 4;

The option is almost excellent, a small shell shock with drifts.
Speed ​​- good acceleration, excellent speed.
Stability - the car can easily roll over.
Handling - small problems with skidding on corners.

### 9 option

Speed ​​- 4;
Sustainability - 5;
Manageability - 4;

The option is very good.
Speed ​​- average acceleration, good speed.
Sustainability is excellent.
Handling - Tight turns.

Conclusions: of course, not only body weight and center of gravity affect our characteristics. But setting the center of gravity correctly will solve some of your problems in the future. I believe that option 6 and 9 are the most acceptable, with option 6 for a car and possibly option 9 for a truck. Why is it possible? Because it must be individually selected and tested. And with pre-configured scripts.