Physical Movement Questions Elementary 2A .

1.v person = 36

v = v man - v wind = 10 - 3 = 7 (m s).

It feels like a north wind.

2.There are 2 5 uphill and 3 5 downhill when going to school. Then there are 3 5 uphill and 2 5 downhill at the end of school.

If the downhill speed is x(m s), then the uphill speed is 2x 3(m s) and the distance is s

So 2s (5(2x 3))+3s 5x=36 (minutes), the solution is x=216s 5

So the time to get home from school t=3s (5 (2x 3))+2s 5x=39 (min)

3.v A = 1800 (18 60) = 5 3 (m s).

Let B catch up with A after t seconds, then: v A 6 60=(v B-v A) t, and the solution is t = 180 seconds.

At this time, B is line s=v B t=5 180=900 meters 1800 meters, so B can catch up with A.

So the average velocity of A v=1800 720=

4.The time for the children to run to the high ground is t = 3000 100 = 30 minutes, and the time for ** to reach the coast is t = 1500 500 = 3 hours = 180 minutes.

So t-t = 150 points. Since the tsunami occurred at 8:30 a.m., it was possible to escape by 11:00 a.m. at the latest.

5.Wrong. Only when time is constant, the speed is proportional to the distance; When the distance is constant, the speed is inversely proportional to the time.

Note: It is not difficult to learn physics well, as long as you have perseverance and perseverance, I believe you will be able to learn physics well.

That's a simple question.

It's all kinematics.

As long as you divide the movement into several independent states, you can make it.

1 is the separation of wind and people. Then synthesize.

2. Analyze the speed of going to and from school separately, and then use the solution equation to find it, which is completely a mathematical problem.

3 is to list the equation separately for two people, and the relationship is 6 minutes more, and then solve the equation.

4. It is assumed that the child is not swept away by the waves. It's just come across the equation for the tsunami and kids.

Time is corresponding, and then the equation is solved.

These are almost math problems.

Mathematics and physics are related, and physics is different from physics, which is just an inner analysis of the movement process.

People who are not good at math are not good at physics.

However, if you are good at math, you must not learn physics if you are not good.

Have time to learn math well first.

5 I read it in the book.

Which direction is the wind speed?

The fifth is wrong, and it can only be said that the other quantity is quantitative.

Little ones read well! Don't be online all the time.

It feels like a north wind.

B can catch up with A. 2) 720 seconds.

5.Wrong.

Oh, yes, I'll do my homework here.

Oh my God, do you have to ask this kind of question? Ask the teacher.

Hey, you're cheating indirectly, are you asking about homework? ~！

I advise you to read more books! Look at it solidly, and you won't do it to find me

I'm your teacher, how can you take the homework I gave you online and answer it!! Is there something wrong with your parents? 1

Such a student should play the board!

The wind speed is 7m s from south to north.

Question 1: Which direction is the wind?

A person is in train A, and sees train B with train A as a reference, and train C moves in the opposite direction, so with the ground as a reference, the following statements about the movement of three trains are impossible (

a.Trains A and B travel in the same direction, and train C travels in the opposite direction.

b.Trains A, B, C, all travel in the same directionTrain A and B travel in the opposite direction, and train C is stationary

Trains A and B travel in the same direction, and train C is stationary, please explain the reason. If a is true, then the speed of A" the speed of B, the speed of C does not require b If it is true, then the speed of A "the speed of B", and the speed of A" the speed of C C If it is true, there is no requirement for the speed of the train of A, B C If it is true, then the speed of A "The speed of B" and the speed of C are not required so it should be abcd is possible, as long as the speed of A is "the speed of B", and the speed of A is the speed of C, B is established, regardless of the speed of A, B and C, C must be established as long as the speed of A and the speed of B, D is established.

To solve this type of problem, first draw a diagram to represent several objects.

A as a reference. A has three situations relative to the ground.

1 When A is at rest, both B and C are moving in opposite directions.

2. A is moving forward, B and C are moving in opposite directions, a or B and C are moving in the same direction (slower than A), C or B and C are stationary.

or B is at rest with C or B is at rest with C or B is at rest with C or C is at rest with B.

3.A moves backwards, and B C and A move faster in the same direction than A.

c. So select all for comprehensive analysis.

Answer D Analysis: Taking the passenger as the reference, the relative direction of movement of the motorcycle is the northwest direction, and the relative movement speed is decomposed into the velocity v0 in the west direction and v1 in the north direction.

Let the speed of the car be V, and the actual speed of the motorcycle V3 is decomposed into the velocity V4 in the direction of due west, and V5 in the direction of due north, then there is V4-V=V0>0 So the speed of the motorcycle V3 must be greater than the speed of the car, option D is correct, and B is wrong.

When V4 >> V1, if V4-V=V0, V5-0=V1, and V0=V1, then the motorcycle is northwest relative to the car, but because the actual westward V4 of the motorcycle is much greater than V5 in the due north direction, the actual speed V3 can tend to be due west, and options A and B are incorrect.

d Passengers sitting in a westbound car and seeing a motorcycle moving northwest indicate that the speed of the vehicle must be less than the speed of the motorcycle relative to the ground, because this can only happen if there is a positive speed difference between the motorcycle and the car.

Hope o ( o

dRelative to the ground, the speed of the vehicle must be less than the speed of the motorcycle.

The car that should be a passenger is in motion, and only the speed of the vehicle must be less than the speed of the motorcycle can produce a passenger sitting in a car heading west to see a motorcycle moving northwest.

Choose C, believe me, 99 points in physics in the high school entrance examination.

In the beginning, the object is at rest, indicating that the two forces are in balance and the direction is opposite.

After that, the direction of the resultant force on the object is always the same as that of f1, so we can know that in t1 time, f1 = f2 (originally) > f2 (now).

It shows that the force of f2 cannot be greater than the original value, and it can be seen from the diagram that only c satisfies the situation.

cBecause f1 is always greater than f2, f2 must have dropped at the beginning and cannot go beyond the starting point.

Please select C! Because f2 only becomes smaller than f1 in t1 time so that the direction of the resultant force is always the same as f1. As for whether it is always linearly smaller, it is not necessarily, in short, it must become smaller than f1.

Without taking into account the drag of air on the bullet, the calculation is as follows:

t=51/340s

v bullet =