What is the traction of a car related to when it is driving at a constant speed

The traction force of a car is equal to the drag it experiences when it is driving at a constant speed.

Of course, the traction of the car is also related to its speed when the car is driving at a constant speed, which should be considered from the power aspect. We know that p (power) = w (work) t (time), which can be deformed as p = f (force) s (distance) t, so.

p=fv, where f refers to traction and v refers to speed, and traction is inversely proportional to speed, which is why some trucks with a lot of loads go very slowly.

When the car is driving at a constant speed, it is related to the degree of concave and convex (roughness) on the surface of the wheels and the gravity of the earth on the car itself, that is, it is related to the pressure and friction on the ground.

Specifically, when the roughness of the contact surface is constant, the greater the pressure, the greater the friction, at this time, the traction force should be increased, otherwise the car will slow down; When the pressure is constant, the rougher the contact surface, the greater the friction, at this time, the traction force should also be increased, otherwise the car will slow down. (On the contrary, get it!)

The power of the car (driving at a constant speed, mostly referring to driving at the maximum speed) so the power at this time is the rated power.

p = fv f is the traction force v at this moment and the speed p is the power at this time.

It is also related to friction (i.e., mass).

The traction force of the car is equal to the drag force when the car is driven at a constant speed, and the drag force is equal to the coefficient of friction multiplied by the mass.

Air resistance, friction on the ground, loss of mechanical friction inside the car, and possibly loss of power due to differentials.

Because p=fv

f is the traction force, v is the speed at this time, p is the power at this time.

Because of the constant motion, the traction force is equal to the positive resistance of the posture: f=f

Traction is also equal to power divided by speed: f = p v

p=w t=fs t=f(s t)=fv so f=p repentance v

Answer: If you don't count other resistance (such as frictional resistance between parts and air resistance), only consider the frictional resistance f between the car and the ground, or f represents all frictional resistance, and let the traction force of the automobile engine be f, then according to Newton's second law, there is:

f f=ma or f=ma+f

When f=f, a=0, when the car is driving in a straight line at a constant speed;

When f f, a 0, the car accelerates uniformly and travels in a straight line;

When f f, a 0, the car decelerates evenly and decelerates in a straight line.

On horizontal ground, gravity g and ground support n are always a pair of balancing forces.

Some people think that the "traction force on the car" refers to the "forward horizontal force exerted by the ground on the driving wheels".This statement is not entirely true, either.

In the following narrative, f, f1, f2, f3, f3, f are combined.

Indicates the magnitude of the force, all of which are positive.

When the engine does not work and the car continues to move forward, the force of the air on it f1 is backward, the horizontal force f2 on the ground facing the driven wheel is backward, and the horizontal force f3 on the driving wheel is backward.

The drag experienced by the car f satisfies:

f=f1+f2+f3

When the engine is working, the car accelerates and drives at a constant speed, the force f1 of the air on it is backward, the force f2 of the ground facing the driven wheel is backward, and the force f3 of the ground facing the driving wheel is forward.

At this time, the resultant force f is satisfied:

f-combined=f3-(f1+f2).

It also seems to make sense if we define F3 as the amount of traction and (F1+F2) as the amount of drag experienced by the car when the engine is working. But in fact, the definition of traction and drag is not like this.

2) The formula can be turned into.

f-sum = (f3+f3)-(f1+f2+f3).

In fact, (f3+f3) is defined as the magnitude of traction, and (f1+f2+f3) is defined as the magnitude of drag.

According to this definition, if F3 2000N, F3 3000N, then the traction magnitude is 5000N

The reason for such a definition is not obvious, so it is generally avoided in books.

The effect of the engine operation is not to change the horizontal force on the driving wheel from zero to f3: but to make the horizontal force on the driving wheel change from backward f3 to forward f3

Recognizing this may help us understand this definition.

When talking about the work of traction, the whole car is treated as a mass point, so that the work of traction is equal to the product of the traction force and the distance traveled by the car.

After the above definition of traction, the output power of the engine (related to gasoline consumption and efficiency) is equal to the power of traction. This is the fundamental reason for adopting the above definition.

The above does not mention the situation where the engine works at a very small power and the car (which turned out to be at a large speed) decelerates and moves. In this case, F3 may be backwards. If it is backwards, then it must be less than f3.

If you go backwards, it is still physically said that there is traction - the magnitude of traction is f3-f3

As long as the drag is constant, the driving force is the same at a constant speed.

The car can be in two states, one that keeps the power constant and the speed constant. Traction force f = p v, so traction force is constrained by both p and v. So when the power is kept constant, when the speed v is smaller, f must be larger, which is greater than the drag f, and the car accelerates.

When accelerating to a certain value vmax, there must be f=p vmax=f, and the velocity is constant at this time.

When the car is running at maximum power and at maximum speed, the traction of the sedan is equal to the drag.

The traction force experienced when the car is driving at a constant speed at different speeds, since it is a constant speed, then f=f is inevitable. F does not change, F does not change. f=p v, the faster the speed, the more power is required to provide sufficient traction f.

It's not about it, it's just about quality.

The faster an athlete runs, the better the performance. But it does not mean that inertia is related to velocity. This is explained by both inertia and Newton's second law.

Let me give you a better example.

The higher the speed, the less likely it is to stop, and it feels like the speed is high and the inertia is large. In fact, inertia refers to the ease with which an object changes its state of motion. Pay attention to the "difficulty"It is not only reflected in the time spent, but also in the rate at which the unit time changes.

i.e. v t is determined, that is, acceleration a is determined. That is, the inertia is determined by the magnitude of acceleration. (In the example, although the speed is large, it takes a long time, but the speed change v is also large.)

From the perspective of Newton's second law: a=f m; With the same magnitude of force, an object with a small m and a large one, it is easy for the object to change its state of motion, and the inertia is small. Vice versa.

Therefore, mass is the only measure of the magnitude of inertia.

Inertia and speed have nothing to do with each other. Because there is no inertia in this world. Saying that inertia has something to do with quality is not blind to the book. It's all mindless people.

Speed has nothing to do with inertia, inertia is only related to the mass of the object (it is recommended to tutor upstairs on junior high school physics). And the faster we usually say the speed of the car, the longer the braking distance is due to the relationship between impulse and momentum. The car is driving at a constant speed on the highway not because of the traction force that causes it to move, but because of the equal friction force and the traction force.

The forward motion of the car is caused by the friction force that is forward.

Because of the constant motion, the traction force is equal to the drag: f=f

Traction is also equal to power divided by speed: f = p v

p=w t=fs t=f(s t)=fv so f=p v

When the car is driving at a constant speed on the highway, the traction force is 6000N, and the resistance of the car is [6000N].If the drag does not change, and the traction force increases, the speed of the car will be [plus the speed of the stupid Kaiwang movement]; If the engine is turned off, the speed of the car will [decelerate.] ]