Which of the physical quantities given below is a vector () A. Quality B. time C. force D. distance

Which of the physical quantities given below is a vector () A. Quality B. time C. force D. distance

Mass, time, distance are only size, no direction of the physical quantity is scalar, is scalar, force is size and direction of the physical quantity is vector

The speed and acceleration of the car when it starts
"When the car starts, the speed is zero and the acceleration is not zero." why?

It's normal to have acceleration and no speed
Velocity needs the time accumulation of acceleration to be v = at. Don't forget t

The speed of car starting is expressed by the acceleration time from 0 to 20m / s. The shorter the time, the greater the acceleration of car starting
The speed of starting and the maximum speed that can be achieved are two important factors in the index system of automobile performance
Important indicators. The speed of car starting is expressed by the acceleration time of car speed from 0 to 20m / s. The shorter the time, the better the performance
The greater the acceleration the car starts. The performance indicators of the two vehicles are listed in the table below
Start speed / S
(acceleration time of 0-20M / s) maximum speed / m · S-1
Car a 8 30
Now, car a and car B are on the same straight road, the front of the car is in the same direction, car B is in the front and car a is in the back,
If the distance between the two vehicles is 110m, vehicle a starts first, and then vehicle B starts after a period of time t0. If the speed of the two vehicles is from 0 to the maximum, the two vehicles will start again
During the time of speed, they all make uniform acceleration linear motion with the maximum acceleration. When car B leaves for 8s, the two cars meet
(1) What is the distance of car a when two cars meet
(2) The time t0 when car a starts before car B

Therefore, the distance traveled by car B: (1 / 2) * 4 * 8 ^ 2 = 128; therefore, the distance traveled by car a when two cars meet is 128 + 110 = 238; the time needed for car a to travel 238: the time for car a to reach the maximum speed: 30 = 8 * t; the distance traveled is (1 / 2) * 8 * (30 / 8) ^ 2

Normal vehicle starting mode, starting with constant acceleration,
If the traction force can remain unchanged, why does the resistance also remain unchanged? If it changes, the resultant force will change, then the acceleration will not be constant. So the resistance must remain unchanged,

There are two parts of the resistance, one is the frictional resistance, the other is the air resistance. The latter is often ignored in the research, and the friction is directly proportional to the positive pressure between the vehicle and the ground. Since the positive pressure between the vehicle and the ground is always equal to the gravity of the vehicle, the friction force remains unchanged

What is the original function of sine function to the third power?

∫(sinx)^3dx
=∫(sinx)^2sinxdx
=-∫[1-(cosx)^2dcosx
=-∫1dcosx+∫(cosx)^2dcosx
=-cosx+(cosx)^3/3+C

How many focal points do the image of the fourth power of X and the image of sine function have?
RT

2

Indefinite integral of quintic power of sine function

S（sinx)^5 dx
=-S(sinx)^4dcosx
=-S(1-(cosx)^2)^2 dcosx
=-S(1-2(cosx)^2+(cosx)^4)dcosx
=-cosx+2/3*(cosx)^3-1/5*(cosx)^5+c

A high number problem of indefinite integral, the recurrence formula of indefinite integral in = ∫ (LNX) ∧ n DX

Theorem
Primitive function UDV = UV primitive function VDU
Here u = (LNX) ^ n, DV = DX
du=n(lnx)^(n-1)dx/x,v=x

Why does (SiNx + cosx) / (SiNx cosx) ^ 1 / 3 for indefinite integral become SiNx cosx

∫［（sinx＋cosx）/（sinx－cosx）^（1/3）］dx
＝∫［1/（sinx－cosx）^（1/3）］d（sinx－cosx）
＝［1/（－1/3＋1）］（sinx－cosx）^（－1/3＋1）＋C
＝（3/2）（sinx－cosx）^（2/3）＋C.

What is the indefinite integral of [2 + (SiNx) ^ 2] / (cosx) ^ 2?

∫(2+sin²x)/cos²xdx
=∫(3-cos²x)/cos²xdx
=3∫(1/cos²x)dx-∫dx
=3tanx-x+C