The mass of a car with rated power P is m. It starts from standstill on a straight road. If the traction of the car remains unchanged during the starting process, the resistance in the process of movement is u times that of the car. What is the maximum acceleration time

The mass of a car with rated power P is m. It starts from standstill on a straight road. If the traction of the car remains unchanged during the starting process, the resistance in the process of movement is u times that of the car. What is the maximum acceleration time

F*a*t=P
a=（F-Umg）/m
T = PM / F / (f-umg)

In the experiment of using the timer to pull the paper through the timer to analyze the speed and acceleration of an object, the motion that can be analyzed should be ()
A. Motion with constant positive value and positive acceleration B. motion with constant negative velocity and negative acceleration C. motion with positive velocity and negative acceleration D. motion with positive velocity and positive acceleration

Because the speed direction of the paper tape will not change, the speed direction will not change. When the paper tape accelerates, the speed direction is the same as the acceleration direction. When the paper tape decelerates, the speed direction is opposite to the acceleration direction. The speed will not change from positive value to negative value. Therefore, a and B are correct, and C and D are wrong

The speed of the car is 10m / s
The speed of the car moving in a uniform straight line is 10m / s. when the car suddenly brakes, the acceleration after braking is 5m / s, and the displacement within 2S after braking is ---?
I make 2.5m, the answer is 10m, which is right?

When the speed of the car moving in a straight line is 10 m / s and the speed of the car stopping is 0 m / s, then
According to V0 = VT at, we can get: 0 = 10-5t, and the solution is: T = 2S
So it takes 2 seconds for the car to brake and stop
The speed at the end of the first second is 5m / s, and the speed when the car stops is 0m / s
So the average velocity in the second second is (5 + 0) / 2 = 2.5m/s
So the displacement in the second second after braking is 2.5 * 1 = 2.5m

How to calculate the acceleration when the car is running at rated power
How to calculate the acceleration when the vehicle is running at rated power and the speed does not reach the maximum value

P = FV, if you know the speed at that time, you will know the traction at that time, and then subtract the relevant resistance, you will get f '= ma, so you can get the acceleration