Questions about car acceleration, questions about the speed at which cars are traveling?

1. The integral method is used to find the acceleration, and the isolation method is used to find the relative force. First, let's assume that there is no relative slippage. Think of the cart and the block as a unit.

If the resultant external force is 25N, then the overall acceleration a=. Looking at the cart separately, the cart is only subject to the friction provided by the block. In addition, the resultant external force of the trolley is derived from the acceleration ma=10n<12n, so the assumption is valid.

Acceleration = . 2. The same method, assuming that there is no relative sliding, find the acceleration 10. then ma=20n>12, then it must be relatively slippery. The acceleration of the trolley, (100-12) 6=

In response to your first question:

When the horizontal tensile force f=25n, the static friction between the block m and the trolley m f=10n The net force of the block m is equal to f-f=15n, the acceleration is that the net force of the trolley m is equal to f=10n, and the acceleration is.

In response to your second question:

When the horizontal tensile force f=100n, the block m and the trolley m are not relatively stationary, and the sliding friction between the two is f= n= mg=12n

The net force on block m is equal to f-f=88n, and the acceleration is 44 3m s2 The net force on the trolley m is equal to f=12n, and the acceleration is 3m s2

Your idea is correct and the answer is wrong.

The internal force of the block and the small workshop = the dynamic friction of the small block = 12 N.

Looking at the horizontal direction of the trolley, only the friction of the block on the trolley is correct, so the trolley acceleration 3 is correct.

It may be that there is a problem with the question, if the dynamic friction factor between the horizontal plane and the car is the same as the dynamic friction factor between the car and the object, it is the solution in the book.

Find the acceleration according to the meaning of the topic The acceleration is the largest at the maximum static friction Also, why do you calculate a1 by dividing by 4 instead of 6? Isn't the mass of the block 6gk?

But when the car is running in the high gear, tight acceleration is often accompanied by active downshifting, and the engine speed goes up first by stepping on the throttle (because most cars only have large torque at higher speeds, torque can be understood as the "strength" or "force" of the car, which is actually the moment, and the "plus" speed of the physical object is proportional to the "strength"), the first speed will be due to the inertia of the vehicle speed, and the passive moment to mention the higher speed (the throttle does not need to be stepped on), at this time, the speed of stepping on the accelerator will soon become higher, but the final transmission of the low gear is relatively low, Therefore, after the rev comes up, you should quickly increase the gear, and the speed of the car will increase rapidly. Manual transmission requires better technology, fast shift and good oil separation, automatic transmission generally urgently step on the throttle, automatic transmission will automatically downshift and then upshift (i.e., kick down).

In addition, the opening and fuel injection volume of the fuel injection nozzle of the EFI vehicle are not only related to the depth of the accelerator, but also related to the size of the stroke of each throttle pressed, so if the displacement is not large enough, you can first step on the accelerator when accelerating sharply, and then quickly close the accelerator, and then step on the accelerator deeply, and come a few times (don't do this at the moment of manual transmission, you can blast a little oil).

Unless you like to play with cars, you usually do it when you are overtaking in an emergency or avoiding a disaster. Under normal circumstances, a quick and deep throttle pedal and a normal throttle increase can cope with the needs.

Regarding the definition of rapid acceleration, the following statement is correct, what is it?

The speed limit on provincial roads (provincial roads) is 60km, the speed limit on national roads is 80km, and the speed limit on expressways is 120km

If there is only one speed limit sign, that is, all cars are limited to this speed, if they are marked separately, then drive according to the signs, such as the speed limit for cars on the general highway is 120, the speed limit for passenger cars is 100, and the speed limit for large trucks is 90

The speeding penalty is according to the proportion of your speeding, with a minimum fine of 50 yuan, a fine of 2000 for 50% of speeding, and a driver's license will be revoked if it is more.

All cars cannot exceed 120km on high speeds

The speed limit may vary from highway to highway, but it cannot exceed 120 km/h

If you want to speed without fines and demerit points, you can only have police cars, fire trucks, military vehicles, and 120 cars.

Moving cars.

From the perspective of physical force: the driving force of the car is that the driving wheel (tire) of the car rotates first, called the driving wheel, and the ground has the effect of friction on the driving wheel, and the direction is the same as the direction of the car, which is the driving force of the car (tractor) f!

The friction between the ground and the driven wheel, the rolling resistance of the tire, and the air resistance (high speed, high air resistance) are the resistance f when the car is moving, which is opposite to the direction of the car's movement. For the front and rear wheel-drive cars, the front and rear wheels are driving wheels, the friction force on the ground to the car is the same as the direction of movement of the car, the driving force increases, and the resistance is the rolling force and air resistance.

Diagram of the general force analysis of the car during driving.

When the driving force f is greater than the drag force f, the car accelerates forward, and the acceleration a is calculated by Newton's second law f-f=ma, where m is the total mass of the car.

When f=f, the acceleration of the car a is equal to 0, the car moves forward at a constant speed, f is determined by the power formula p=fv, where the maximum power p of the car is limited, it is determined by the engine, and can be regarded as a certainty. With the increase of the speed v of the car, the traction force f of the car will decrease, when the driving force f decreases to equal to the resistance f, the acceleration of the car a = 0, the speed of the car reaches the maximum value, and the car will move at a constant speed at the maximum speed at this time! Absolutely:

Turn off the accelerator for an hour, the actual power of the car becomes smaller, the driving force f decreases, the car slows down, the resistance of the car decreases, until the acceleration of the deceleration a=0, the car will move at a uniform speed with another speed value! The situation of the car when driving at low throttle is the same as in the above analysis, except that the actual power is less than the rated power. So:

The maximum speed of the car is determined by the maximum power of the car engine and the resistance f when the car is driving (the friction between the ground and the driven wheels, the rolling resistance of the tires, the air resistance (high speed, high air resistance, etc.)!

There are many factors that affect it, such as vehicle speed, ground level, tire condition, etc. Theoretically, the normal acceleration is a = -6m s2.

Acceleration is the ratio of the amount of change in velocity to the time it takes for this change to occur δv δ t, which is a physical quantity that describes how quickly an object changes in velocity, usually expressed in a and in m s 2. Acceleration is a vector quantity, and its direction is the direction of the change in the velocity (quantity) of the object, which is the same as the direction of the resultant external force.

The accelerator pedal increases the force of the engine, and the engine speed increases.

The average car can accelerate from zero to 100km h in 10 seconds.

The average acceleration is, i.e., approximately, and the maximum acceleration can reach about that. In the case of a supercar, the acceleration can exceed 1 g.

The illustrations are sharp and random on the Internet.

When the car is driving, it can accelerate by pressing the accelerator pedal and slow down by pressing the brakes. Of course, you have to step on the accelerator and brake slowly, otherwise the car will run very unsmoothly and the passengers will be very uncomfortable. When you need to accelerate and decelerate, it also depends on the speed of the car.

When the car needs to accelerate at low speed, it is necessary to look at the engine tachometer while stepping on the accelerator to upshift in time (generally the car upshifts at 1500-2000 rpm). Similarly, when slowing down at low speeds, apply the brakes and press the clutch to prepare for downshifting. When the car is running at high speed, when the gear has reached the highest gear, you can directly step on the accelerator when you accelerate again.

If you just want to slow down a little at high speed, just release the accelerator pedal and feel like you are slowly pressing the accelerator at your desired speed. If the car needs to slow down as soon as possible when running at high speed, you can release the accelerator and press the brake pedal directly, and if the speed is very low, you need to press the clutch. The speed of high-speed driving and low-speed driving is generally defined at about 50-60 miles, more than 60 miles can be regarded as high-speed driving, and less than 50 miles is considered low-speed driving.

Of course, it also depends on the specific model and displacement. The most important thing to master when driving is to have the right gear and speed (commonly known as speed recognition). Don't:

The gear is high at low speed and low at high speed. High gears at low speeds damage both the engine and gearbox, and low gears at high speeds are very fuel-intensive for the car, and it is easy to raise the water temperature and make a lot of noise. It's best not to jump gears when upshifting, and it's not a big deal to go straight from 1st gear to 3rd gear.

However, after a long time, there will be damage to the gearbox, because the gears of the gearbox need to have a process, and if the gear ratio changes too much, the gearbox gears will be damaged. It doesn't matter when downshifting, it's normal to go straight from 3rd gear to 1st gear.

Hello, the official certified technician of the car medical network is happy to answer for you, mainly the cooperation between the clutch and the accelerator brake, this is a skilled operation that practice makes perfect, so there is nothing too good to knock on the door, more operation, more contact is good, I hope my answer will help you!

Of course, the speed is controlled by the brakes and gears, and the throttle.

By gear, brake and throttle!

and throttle with clutch plus gear to control.