"Inference of Uniformly Variable Speed ​​Linear Motion (2)" Research on Uniformly Variable Speed ​​Linear Motion PPT

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"Inference of Uniformly Variable Speed ​​Linear Motion (2)" Research on Uniformly Variable Speed ​​Linear Motion PPT

Part One: Basic Review

Speed ​​formula v=v0+at, when v0=0, v=at

Displacement formula x=v0t+12at2, when v0=0, x=12at2

v2-v20=2ax, when v0=0, v2=2ax

Average speed formula v-＝v0＋v2＝vt2

The instantaneous velocity of the displacement midpoint vx2＝ v20＋v22

Difference-by-difference equation Δx＝xⅡ－xⅠ＝aT2

PPT on the inference of linear motion with uniform speed, part 2: combination of lecture and practice

Application of Several Proportional Formulas for Uniformly Accelerated Linear Motion with Initial Velocity of Zero

(1) Equally divided by time (assume equal time intervals are T)

The ratio of the instantaneous speed at the end of 1T, the end of 2T, the end of 3T, ..., and the end of nT v1:v2:v3:...:vn=1:2:3:...:n

The ratio of displacements within 1T, 2T, 3T, ..., nT x1:x2:x3:...:xn＝

12:22:32:…:n2

Within the first T, within the second T, within the third T,..., the ratio of displacements within the nth T is x1:x2:x3:...:xn=1:3:5:...:(2n-1 )

(2) Divide into equal parts by displacement (assuming equal displacement is x)

The ratio of the final speed when passing through the first x, the first 2x, the first 3x,..., the first nx v1:v2:v3:...:vn=1:2:3:...:n

The ratio of the time taken to pass through the displacement of the first x, the first 2x, the first 3x,..., the first nx t1:t2:t3:...:tn=1:2:3:...:n

The ratio of the time taken to pass through consecutive equal displacements t1:t2:t3:...:tn=1:(2-1):(3-2):...:(n-n-1)

(Multiple choice) (2019•West Lake School Level Simulation) How many water balloons can stop bullets? The "National Geographic Channel" experiment confirmed: four water balloons are enough! Four identical water balloons are arranged horizontally next to each other, and the bullets in the water balloons move in a straight line at a uniform speed in the horizontal direction. If it happens to be able to penetrate the fourth water ball, it can be determined ()

A. The bullet travels the same amount of time in each water ball

B． From the question stem information, the time ratio for the bullet to pass through each water ball can be determined.

C． The speed of the bullet changes the same in each water ball

D． The instantaneous speed of the bullet passing through the third water ball is equal to the average speed of the entire journey.

Calculation of catch-up and encounter problems

1. When discussing issues of pursuit and encounter, we must grasp one condition and two relationships.

One condition: equal speed is the critical point for whether the two objects catch up (or collide), the maximum distance, and the minimum distance. This is the entry point for solving the problem.

Two relationships: time relationship and displacement relationship. Finding the quantitative relationship between the displacements of two objects by drawing a schematic diagram is a breakthrough in solving the problem.

If the two objects start at the same time, the time of the two objects is equal, so it is necessary to formulate equal velocity equations and displacement equations.

2. Commonly used methods to answer questions about pursuit and encounter

physical analysis

Seize the key point of "whether two objects can reach a certain position in space at the same time", carefully review the questions, explore the implicit conditions in the questions, establish a scene of the movement relationship of the objects in your mind, and draw a schematic diagram of the movement to find out Displacement relationship

Image method

Draw the two velocity-time graphs in the same coordinate system, and then use the graph to solve the problem

PPT on the inference of linear motion with uniform speed, part three: [Exercise to achieve standards]

1. (2019·Xi'an High School Grade 1 Test) A freight train runs at a constant speed on a straight railway at a speed of 8 m/s. Due to a scheduling error, there is a passenger car 600 m behind with a speed of 8 m/s.

Approaching it at a speed of 72 km/h. The driver of the bus immediately applied the brakes after noticing this, but the bus had to coast 2,000 m before it could stop. beg:

(1) What is the acceleration of the bus when it is taxiing?

(2) After calculation, determine whether the two cars will collide.

2. (2019•Chengdu Test) A car is waiting for a green light at an intersection. When the green light turns on, the car starts driving at an acceleration of 3 m/s2. At this moment, a bicycle comes at a constant speed of 6 m/s and comes from behind. Overtake the car.

(1) After the car starts from the intersection, how long does it take before it catches up with the bicycle? The two cars are farthest apart? What is the distance at this time?

(2) When does the car catch up with the bicycle, what is the speed of the car at this time?

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"End of Chapter Review Lesson" Research on Uniform Speed ​​Linear Motion PPT:

"End of Chapter Review Course" Research on Uniform Speed ​​Linear Motion PPT Consolidation Layer Knowledge Integration [Core Quick Filling] 1. Laws of uniformly variable linear motion (1) Speed ​​formula: _________. (2) Displacement formula: _________. (3) Speed-displacement relationship formula: _________. 2. uniform..

"Optimization Summary of this Chapter" Research on Uniform Speed ​​Linear Motion PPT:

"Optimization Summary of this Chapter" Research on Uniformly Variable Speed ​​Linear Motion PPT Integrate and Improve Common Methods for Obtaining Uniformly Variable Speed ​​Linear Motion Since there are many formulas in the kinematics part, and the formulas are related to each other, some of the questions in this chapter can often be solved in one question Many solutions. When solving problems...

"Application of Laws of Uniformly Variable Speed ​​Linear Motion" Research on Uniformly Variable Speed ​​Linear Motion PPT Courseware:

"Application of the Laws of Uniformly Variable Speed ​​Linear Motion" PPT courseware for the study of uniformly variable speed linear motion Part 1 Contents: [Learning Objectives] 1. Master the two basic formulas of uniformly variable speed linear motion. 2. Master the three average speed formulas and their applicable conditions, and be able to apply the average speed formula...

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Update Time: 2024-10-31

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