Which of the following objects is closest to a uniform linear motion within 1 min, and sorted

Building B moves with the earth.

- The building follows the Earth, the angular velocity and linear velocity are very small, and it can be considered that the velocity magnitude direction is almost unchanged in a short period of 1 min.

c. The person on the escalator moves with the escalator.

-The person follows the escalator, although it rises or descends diagonally, and it moves in a straight line in a short period of 1 minute and the speed does not change much.

a Person is walking in the hallway.

- People walking in the corridor, maybe everyone thinks that the speed of movement is unchanged and moves in a straight line, on the surface, but everyone has this feeling, when people walk, their feet always alternate back and forth, and the human body will rise and fall, from the plane to see that people are moving in a straight line, but people are three-dimensional Three-dimensional space People are not moving in a straight line, so the three are compared in this order b,c,a,

Building b stands on the earth, that is, the earth revolves around the sun, and the orbit of the earth is an ellipse. The line between the center of the sun and the earth (center) is the same as the area of the sector swept in the earth's orbit at the same time. Therefore, the speed of the Earth's revolution is slowest at aphelion and fastest at perihelion.

Although it is a variable speed movement, it is still relatively close to a constant speed. There is also the case of the rotation of the Earth; Relatively close to uniform linear motion in one minute.

c The escalator movement is theoretically at a constant speed! There are many kinds of escalators, and people top them in the morning, and the steps also change direction in a cycle! The premise of a minute is very problematic.

The movement of people in a straight corridor is much worse than that of B!

There are a lot of questions in this question.

If the ground is used as a reference, the building is in a static state. The elevator motion in c must be a uniform linear motion. The person in A walks is the last.

I agree with you, I also read the physics book just now, and if it's wrong, please I don't agree, the direction is southeast, northwest, and this satisfies the property of the displacement (and the size of the displacement). A straight line with a constant velocity cannot be said to be pointing, unless the direction is given in the title! Tell me oh o(o

A is definitely true, because uniform linear motion means that the velocity does not change, and this constant refers not only to the magnitude, but also to the direction, and if the direction of the velocity changes, it is not called uniform linear motion.

b displacement is a vector and distance is a scalar quantity.

c The speed of motion refers to the magnitude of the velocity, and if the two velocities are in opposite directions, the displacement is different.

d You say you know, but don't say it.

I didn't see it clearly just now that it was a uniform linear motion, so I made a mistake, I'm sorry. Agree with what was said downstairs.

a。The direction of uniform linear motion is constant.

b。Displacement has direction and is a vector quantity. The distance is a scalar quantity.

From your point of view, I would like to explain the situation of options A and B.

Option A is right. Since the displacement of an object moving in a straight line at a uniform speed is the same every 1 second (the direction is of course the same), the displacement in any 2 seconds must be equal to 2 times the displacement in 1 second. (Uniform linear motion refers to the motion with constant velocity in a single direction, that is, the motion with constant velocity).

Option b is wrong. ReasonAs you said, displacement (which is a vector) cannot be said to be equal to distance (scalar), and it must be stated that it is "the magnitude of displacement" when making comparisons.

Depending on the options, the title of your question should be: "An object moves in a straight line at a uniform speed".

Rather than "an object is transported in a straight line at a uniform speed".

So you should choose C

From v = v0 + at, it can be seen that only when the initial velocity is zero, the final velocity of the object is proportional to time, otherwise it is not , a is wrong.

From x = v0t + 1 2 at: only when the initial velocity is zero, the displacement of the object is proportional to the square of time, otherwise it is not , b is wrong.

From a = v δt : velocity change δv = a· δt , uniform velocity motion, a unchanged , so , δv is proportional to δt, c pair.

If it is a uniform deceleration linear motion, the displacement may increase with time, such as the deceleration motion of the car brake, the displacement increases!! d False.

Uniform linear motion.

1. The speed remains the same.

2. S=XT displacement is proportional to time.

Answer BA, the object falling from the upper floor, due to the influence of the cover to the heavy wisdom, the uniform speed is getting faster and faster, it is an accelerated movement, so A does not meet the topic;

B. Because the conveyor belt may do uniform linear motion, the carton above also does uniform linear motion with the conveyor belt, so B is in line with the topic;

c. The aircraft taxiing along the runway is subject to the resistance of the ground, and the speed is getting smaller and smaller, and it is not moving in a straight line at a uniform speed, so C does not meet the topic;

D. The speed of the train entering the station is getting slower and slower, and it is not a straight line movement before the constant speed, so D does not meet the topic

Therefore, choose B

A. The speed of the train entering the station is getting slower and slower, and it is not moving in a straight line at a uniform speed, so A is wrong;

B. The speed of the football rolling on the grass after leaving the foot is becoming more and more insidious, and it is not a uniform linear motion, so B is wrong;

c. The speed and direction of the customer's movement on the escalator remain unchanged, which is a uniform linear motion, so C is correct;

d. The direction of the "Beidou" satellite, which rotates around the earth at a uniform speed, is constantly changing, and it is not a straight line motion at a constant speed, so D is wrong

Therefore, C

It's a simple matter of physical variables.

The distance is equal to the time multiplied by the speed.

It only makes sense to study the other two quantities when one quantity is prescribed.

When the distance is determined, time is inversely proportional to speed.

When time is determined, the distance is proportional to the speed.

When the speed is determined, the distance is proportional to the time.

aUndetermined time.

bUndetermined distance.

c is directly wrong, the speed is the same, and the distance is proportional to the time.

1)s1=s2=>v(t+5)=at^2/2=>1*(t+5)=>t=(5+5�0�55)/2;

2) When the phase difference distance is the largest, that is, when the velocity of the two objects is equal, that is:

v(a)=v(b)=>1=> Nian with t=>s=s1-s2=v(a)*(t+5)-at 2 Aberdeen Finger Height 2=1*(

Let t meet in seconds, then 5*1+1*t=square, simplify to get t-square-5t-25=0 to solve it yourself, before ab meet, the distance between them and chunchang is increased by five eggplant chops, and then decreases, when the speed of b is equal to a, the distance of sentong is the largest, that is, the solution is seconds, at this time, the total distance of a movement is, and the distance of movement in seconds is square is equal to so the maximum distance is.

The phone called, tired to death, hope to help you.

Solution: Deficit (1).From the meaning of the title:

If the time of t1 catches up, then there is: at1 2 2 = vt1 + vt (where t1 2 is the square of time t1, and the regret difference t in vt is 5 seconds), bring in the data, get: t1 = 8 seconds (2), when the distance is maximum, the two velocities are equal, and when the speed is equal, b uses t2 when the pin is in front of the eye, then there is:

at2=v, solution: seconds, at this time, the maximum distance = vt+vt2-at2 2 2 = meters.

The solution yields t=(5+5 times the root number 5) 2s2The speed of the two is the same, including the largest distance when dismantling, and B went to Qing Zheng when answering the old song.

a. The distance of the object is s=vt, that is, the distance from the DU is determined by both speed and time, so this option is wrong

b, in the straight public road is meaningful.

In the description is a straight line motion, the distance traveled per minute is 1000 meters, and does not mean that the car is moving at a constant speed, it is possible that in this minute, the first half minute travels 800 meters, the second half minute travels 200 meters, then it is not a uniform motion Therefore, this option is wrong

c. The speed of motion of uniform linear motion remains unchanged and has nothing to do with the distance, so it does not conform to the topic d. The speed of motion of uniform linear motion remains unchanged, according to s=vt, the longer the time required, the longer the distance that the object passes through with uniform linear motion, and the distance that the object passes through with uniform linear motion is proportional to the time required

Therefore, choose D