"Important corollary of linear motion with uniform speed" Research on linear motion with uniform speed PPT

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"Important corollary of linear motion with uniform speed" Research on linear motion with uniform speed PPT

Part One Content: High Frequency Test Point 1 The average speed of linear motion with uniform speed

[Knowledge Comprehensive]

1. The general expression of average speed v=st.

2. In uniform linear motion, the average speed of a certain process is equal to the average of the initial and final speeds, that is, v=12(v0+vt).

Proof: As shown in the figure is the vt image of linear motion with uniform speed,

Then the displacement within t time is s=12(v0+vt)t,

Therefore, the average speed is v=st=12(v0+vt).

3． In uniform linear motion, the instantaneous speed at the middle moment of a certain process is equal to the average speed of the process.

That is, vt2=v=12(v0+vt).

Prove: In linear motion with uniform speed, for the time period from 0 to t2,

There are: vt2=v0+a·t2;

For the time period from t2 to t, there is: vt=vt2+a·t2;

By combining the two equations, we can get vt2=12(v0+vt)=v.

[Training Unicom]

Typical example 1 It lasted 20 s and moved 50 m. Find the maximum speed of the car during the above motion.

[Regular method]

Basic methods for choosing formulas skillfully when solving problems

(1) If there is no displacement s in the problem and no displacement is required, the speed formula vt = v0 + at is generally used;

(2) If there is no terminal velocity vt in the problem and no terminal velocity is required, the displacement formula s=v0t+12at2 is generally used;

(3) If there is no movement time t in the question, there is no need to find the movement time. Generally, the derived formula vt2-v02=2as is used;

(4) If there is no acceleration a in the question, and it does not involve the issue of acceleration, it is more convenient to calculate it with v=st=v0+vt2.

[Instant training]

1. [Multiple Choices]The car starts from rest and starts to move in a straight line with uniform acceleration. After 1 s, the speed reaches 3 m/s, then ()

A. The average speed of the car during this 1 s is 3 m/s

B. The average speed of the car during this 1 s is 1.5 m/s

C. The displacement of the car in this 1 s is 3 m

D. The acceleration of the car is 3 m/s2

2. [ Multiple Choices It is known that the telephone poles P and Q are 60 m apart, and the speed of the car when passing the telephone pole Q is 15 m/s, then the following statement is correct ()

A. The speed of the car passing the telephone pole P is 5 m/s

B. The acceleration of the car is 1.5 m/s2

C. The distance between P and O is 7.5 m

D. The time it takes for the car to pass the telegraph pole Q from departure is 9 s

Important Corollary of Uniform Speed ​​Linear Motion PPT, Part 2: High-frequency Test Point 2 Application of Important Corollary Δs=aT2

[Knowledge Comprehensive]

1. Difference-by-difference formula: Within any two consecutive equal time intervals T in uniform linear motion, the difference in displacement is a constant, that is, Δs=sⅡ-sⅠ=aT2.

2. Application: First, it is used to determine whether an object is moving in a straight line at a uniform speed, and second, it is used to find acceleration.

3． Extension: For two non-adjacent displacements in the same time period in uniformly variable linear motion, there is sm-sn=(m-n)aT2 (this formula is often used in the processing of experimental data, such as finding objects based on printed paper tapes acceleration).

4． Calculate the acceleration of the object based on the printed paper tape: As shown in the figure, it is a paper tape printed by the dot timer. The time interval between two adjacent counting points is T, and the displacement of each segment is as shown in the figure. Now to require the acceleration of an object, the following methods can be used:

[Training Unicom]

[Typical Example 2] In the experiment of "Measurement of the Acceleration of Uniform Speed ​​Linear Motion", a paper tape as shown in the figure was obtained, and 0, 1, 2, 3, 4, 5, 6 were taken in chronological order. There are seven counting points in total, and there are four punched out points between each two adjacent counting points that are not drawn. Use a scale to measure the distances from points 1, 2, 3,..., 6 to point 0, which are 8.69 cm respectively. , 15.99 cm, 21.87 cm, 26.35 cm, 29.45 cm, 31.17 cm, the dotting timer will dot every 0.02 s. Find the acceleration of the object.

[Regular method]

(1) The process of answering this question is equivalent to dividing the paper tape into two parts. This method is also called the overall dichotomy method.

(2) If the paper tape has an odd number of segments, the middle segment is often not used. For example, if there are 5 segments, the third segment is not used; a1=s4-s13T2, a2=s5-s23T2, and then take the average, that is, a=a1+a22=s4+s5 －s1＋s26T2, which can make full use of the given data and effectively reduce the accidental error caused by only two displacement measurement data.

Important Corollary of Uniformly Decelerating Linear Motion PPT, Part Three: High-frequency Test Point Three Two Types of Uniformly Decelerating Linear Motion

[Knowledge Comprehensive]

[Typical Example 3] An airplane can obtain an acceleration of a=6 m/s2 when it lands and performs uniform deceleration in a straight line. The speed of the airplane when it lands is v0=60 m/s. Find the time it takes to land within t=12 s. Gliding distance.

[Typical Example 4] As shown in the figure, the ball slides upward along the slope from the middle of the sufficiently long slope at a speed of 6 m/s. It is known that the acceleration of the ball moving on the inclined plane is 2 m/s2. Find the displacement of the ball after 2 s, 3 s, 4 s, 6 s, and 8 s respectively. (When the ball moves on a smooth slope, the magnitude and direction of the acceleration remain unchanged)

[Instant training]

6． A car is traveling at a constant speed of 10 m/s. When encountering an emergency, it suddenly decelerates and brakes with a constant acceleration of 2 m/s2. Then starting from the moment of braking, the displacement of the car within 6 s is ()

A. 24m B. 25 m

C. 60m D.96m

7． [Multiple Choices]An object slides upward along a smooth slope with an initial velocity of v0 = 8 m/s. The acceleration is 2 m/s2. After reaching the highest point, it goes back with the same acceleration. sports. Which of the following statements is correct ()

A. The velocity at the end of 1 s is 6 m/s

B. The velocity at the end of 3 s is zero

C. The displacement in 2 s is 12 m

D. The displacement in 5 s is 15 m

Keywords: Free download of PPT courseware for compulsory course 1 of high school physics in Lu Ke Edition, download of important corollaries of linear motion with uniform speed, PPT download of research on linear motion of uniform speed, .PPT format;

For more information about the PPT courseware "Research on Uniform Speed ​​Linear Motion and Important Corollaries of Uniform Speed ​​Linear Motion", please click on the "Research on Uniform Speed ​​Linear Motion PPT Important Corollaries on Uniform Speed ​​Linear Motion" PPT tag.

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Update Time: 2024-09-08

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