# Physics of Automobile Drifting Question?

• KidWonder
In summary, the conversation discusses the physics of drifting, with a focus on the role of the front and rear wheels in causing the car to turn and maintain a constant velocity. It also explains the technique of "E-braking" used by drifters to initiate a drift and maintain control while sliding.
KidWonder
Ok, this has been on my mind all day. Sorry if it's a stupid question, I'm still a H.S student trying to figure out to study Mechanical Engineering or Physics.

But moving on...

Ok, so the engine propels the vehicle at a constant velocity.

If the front wheels turn and the back end slides does this mean the angle of the wheel turning balances out to the velocity of the vehicle causing the rear end to be angled but still go at a constant velocity in a straight line?

Front Wheels= Cause rear end of vehicle to angle

Engine (RWD)= Cause car to propel foward even when front wheels are turned.

Thanks Guys
God bless

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I'm having a little trouble understanding your question, but here's my understanding of the physics of drifting.

First let's assume an ideal car: unless someone turns the steering wheel, all four wheels are parallel--let's call the line they're parallel to the y axis, and let the z-axis be toward the sky. (y would be forward, x would be right.) Fix the coordinate system to move and rotate along with the car. (So the car moves in the x-y plane. If it's not sliding or drifting, it always moves in the y direction).

Assume the wheels rotate without resistance. (I.e., there's no friction against movement in the y direction.) When the steering wheel is turned, the front wheels angle; physically this has the effect of imparting a torque about the z-axis on the car. If you turn the steering wheel clockwise, the front wheels cause the car to turn right, and (using the right hand rule) the torque on the car is in the negative z direction.

Now there is some finite friction between the wheels and the road, so the wheels can slide in the x-direction. Since there is friction against the rear wheels moving in the x-direction, there's a torque on the car when when the rear wheels are sliding but the front wheels aren't. If the rear wheels are sliding to the left, the rear of the car feels a force to the right, so if the rear wheels slide to the left, the car gets a torque in the positive z direction.

So if the car is turning to the right and the wheels are sliding to the left (as in a drift), the rear wheels' slide causes a torque which acts against the steering.

Now the key to drifting, I believe, has to do with the changes in the coefficient of friction that result from the car "peeling out." Here's what I'm talking about: you've seen high-powered cars in drag races where just as the driver hits the accelerator (or pops the clutch), the car basically stands still while the tires spin (usually accompanied by some smoke... "burning out"). This is because once the wheels begin to spin without gripping the road, the coefficient of friction between the wheel and the road drops dramatically. Good drag race drivers want to maximize their acceleration, so they try to reduce "wheelspin" in order to maximize the coefficient of friction between the wheels and the road. (This is basically an example of the difference between static friction and kinetic friction. Kinetic friction is almost always smaller than static friction.)

Now back to drifting. Since the frictional force of the back wheels sliding works against the steering torque, you can get better turning (overall) torque by reducing the coefficient of friction between the back wheels and the road. As explained in the last paragraph, the wheels have a lower coefficient of friction when they're spinning relative to the road, i.e. "peeling out". So you get more turning torque when your back wheels are peeling out during the drift. You'll notice that drifters don't get a good drift if the back wheels are rolling along with the road (in the y direction), they ALWAYS start peeling out when they need to drift through a tight turn. This is why drifters "tap the clutch" to initiate a drift--putting the clutch in for a moment causes the engine to rev up, and when they release the clutch, the engine makes the rotation of the wheels dramatically increase, so they start peeling out.

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In a drift contest, the front wheels are turned slightly inwards of the direction that the car is moving, so that the car continues to turn while it's moving forwards because the force between front tires and pavement result in the pavement generating an inwards force on the tires which transfer that force to the rest of the car. Even though the rear tires are spinning and sliding, and angled inwards of the direction the car is moving, the force between rear tires and pavement results in the pavement generating a forwards and inwards force on the tires which transfer that force to the rest of the car.

Since the rear tires are sliding, the front tires will have more lateral (sideways) grip than the rear tires, so the driver has to adjust the steering to reduce the inwards force related to steering to keep the car from getting too far sideways.

Most drifters use a technique called "E-braking" where they go into a turn at a high speed, push the clutch in, turn hard into the turn, pull the emergency brake (locking the rear differential, making the rear tires stop rotating). Now that the rear tires have lost grip with the road they start to follow the original velocity vector which is tangent to the curve. the front tires have enough friction to hold the car, but The driver reengages the clutch and accelerates the rear tires just to the point where they have some grip (hovering on the coefficient of static friction) causing the car to snap back. for a more sustained slide the driver just alternates pulling the E-brake with the clutch pushed and pushing the power, all the while guiding the car's trajectory around the curve.

I can say that automobile drifting is a complex phenomenon that involves principles from both physics and mechanical engineering. The key to understanding drifting is to look at the forces acting on the car.

Firstly, the engine does play a role in drifting as it provides the necessary power to propel the vehicle forward. However, it is not the only factor. The key to drifting is the balance between the front and rear wheels.

When the front wheels turn, they create a lateral force on the car, causing it to slide or drift. At the same time, the rear wheels continue to propel the car forward, maintaining a constant velocity. This balance between the lateral force and the forward force is what allows the car to drift in a controlled manner.

In addition, the angle at which the front wheels turn also plays a role in the drifting process. The greater the angle of the front wheels, the greater the lateral force and the more the car will drift. This is why skilled drifters are able to control their drifts by adjusting the angle of their wheels.

So, in summary, drifting is a result of the balance between the lateral force created by the front wheels and the forward force created by the engine and rear wheels. It is a complex interaction of forces and requires a thorough understanding of physics and mechanical engineering to truly master. I hope this helps answer your question and good luck with your studies!

## 1. What is the physics behind automobile drifting?

Automobile drifting is a driving technique where the driver intentionally oversteers to lose traction and cause the car to slide sideways. The physics behind this involves the car's tires losing grip on the road surface due to a combination of speed, weight distribution, and steering angle. This loss of grip creates a force called lateral force, which causes the car to slide.

## 2. How does the weight distribution of a car affect its ability to drift?

The weight distribution of a car plays a crucial role in its ability to drift. A car with a higher weight distribution towards the back will have more traction on the rear tires, making it easier to initiate a drift. However, if the weight is distributed too much towards the front, the car may understeer and not be able to drift effectively.

## 3. What role do tires play in automobile drifting?

Tires are essential for automobile drifting as they are the only point of contact between the car and the road surface. The type of tires, their condition, and the amount of grip they provide can greatly affect the ability to drift. Tires with a lower traction coefficient, such as racing slicks, are ideal for drifting as they allow for easier loss of traction and sliding.

## 4. How does the speed of the car affect drifting?

The speed of the car is a crucial factor in drifting. As the speed increases, the centrifugal force acting on the car also increases, making it easier to initiate and maintain a drift. However, if the speed is too high, it can make the car difficult to control and potentially lead to a loss of control.

## 5. Can the shape and design of a car affect its ability to drift?

The shape and design of a car can also play a role in its ability to drift. Cars with a longer wheelbase and a lower center of gravity are generally more stable and easier to control during a drift. Additionally, a car with a rear-wheel-drive system will have better weight distribution and traction, making it more suitable for drifting compared to a front-wheel-drive car.

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