"Scientific Inquiry: Changes in Speed" The World of Movement PPT Courseware 3

"Scientific Inquiry: Changes in Speed" The World of Movement PPT Courseware 3

[Experience] Whether the speed of moving objects changes

Activity 1: Ride a bicycle freely down the slope and feel the change in speed.

Activity 2: Xiao Ming is conducting a 100-meter race test on the playground.

(1) During the process of riding a bicycle down the top of the slope, the speed of the bicycle ________ (optional "increase", "decrease" or "unchanged").

(2) When Xiao Ming ran the middle distance, his speed _______ (optional "change" or "unchanged").

Tips: (1) Make it bigger (2) Just fill it in according to your actual feeling

pre-study questions

1. What are the general processes of scientific inquiry activities?

2. How to collect data?

3. How to prove experimentally that the speed of an object has changed?

Explore whether the speed of an object changes during movement

Consider the following questions based on the activities in "Experience":

1. In the "experience", based on the movement of the bicycle and the person, ask whether the speed changes in the middle section? This is ________ in scientific inquiry. The rate of response changes or does not change, which is a ________ in scientific inquiry.

Tips: Raising questions about the phenomena you see and expressing them verbally or in writing is the first step in scientific inquiry; putting forward your own opinions based on observations is conjecture and hypothesis.

Reference answers: Asking questions, conjectures and assumptions

2. How to conduct experiments to collect evidence to prove that your conjecture is correct?

Reference answer: You can search for relevant scientific information from public information sources through surveys and research; you can also collect data through experiments. When collecting evidence, you should operate in a standardized manner, seek truth from facts, and have a rigorous and objective scientific attitude.

3. Use a small ball instead of a bicycle, use an incline instead of a downhill road, and explore the changes in speed (as shown in the picture).

(1)Ask a question

When the ball slides down the slope, does the speed of its middle section (AD) change?

(2) Conjectures and assumptions

Based on life experience, our group’s guess is: speed changes.

Knowledge summary

1. Scientific inquiry

1.Ask a question

2. Design experiments

3. Conduct experiments

4. Gather evidence

Through investigation and research, relevant scientific information can be found from ___________, and data can also be collected through _____.

2. Experimental research

1. Exploration steps:

2. Research report:

(1)_________. (2) Conjectures and assumptions.

(3)___________. (4) Experimental data. (5) Explore the conclusion.

【Expansion】

As shown in the picture, the dot timer is a tool for measuring time. The paper tape driven by the moving object passes through the dot timer. The points marked on the paper tape record the time of the object's movement. The points on the paper tape also represent the position of the moving object at different times. By studying the intervals between points on the paper tape, you can analyze the movement of the object.

Test Points Experimental Research on the Movement Speed ​​of Objects

[Typical example] (2012 Weifang High School Entrance Examination) In order to save raw materials and make it easier for users to use, mosquito-repellent incense manufacturers must produce various mosquito-repellent incense with different specifications according to the burning speed of mosquito-repellent incense. There is a kind of mosquito-repellent incense as shown in the picture. Please design an experiment to measure the normal burning speed of the mosquito-repellent incense. The requirements are:

(1) Write down the required equipment;

(2) Explain the measurement method.

[Idea Guide] The key to solving the problem: clarify the physical quantity that needs to be measured, that is, the length of a small section of mosquito coils and the time required to burn this small section of mosquito coils. The equipment is determined by the physical quantities that need to be measured.

[Concise Lecture and Analysis] This question examines the experimental investigation of the speed of objects. (1) According to the speed calculation formula v=s/t, to measure the normal burning speed of mosquito-repellent incense, it is necessary to measure the length of mosquito-repellent incense burning and the corresponding burning time; measuring the length requires a scale and thin cotton thread, and measuring the time requires a stopwatch. , regarding the experiment of mosquito-repellent incense, there should be mosquito-repellent incense, and matches must be used to light the mosquito-repellent incense;

(2) Since mosquito coils are spirally coiled, the length must be measured using the method of converting curves into straight lines. Specific method: ① Take a small piece of mosquito-repellent incense, use a thin cotton thread to stick it closely to the mosquito-repellent incense, mark the two end points, straighten the cotton thread, and use a scale to measure the distance between the two marks as s; ② Use a match to light the mosquito-repellent incense and time it. The time it takes for the mosquito-repellent incense to burn out completely is t; ③Then the burning speed of mosquito-repellent incense is v=s/t.

1. In the process of scientific inquiry, an important link is to conduct experiments and collect evidence, the purpose of which is ()

A. To understand the significance of the questions raised

B. To put forward your own point of view

C. To prove that your point of view is correct

D. To prove whether your point of view is correct

[Analysis] Choose D. This question examines the process of scientific inquiry. In the process of scientific inquiry, we first ask questions, then make conjectures, design experiments and formulate plans, and then conduct specific experiments and collect evidence, with the purpose of proving whether the questions raised are correct.

2. A sprinter ran along a straight line for 5 s and covered a distance of 16 m in the first 2 s.

After passing a distance of 30 m in the next 3 s, the average speed of this athlete in the next 5 s is ( )

A.8 m/s B.10 m/s C.9 m/s D.9.2 m/s

[Analysis] Choose D. This question examines the application of average speed. The total distance traveled within 5 s is s=16 m+30 m=46 m, which is obtained by using the formula of average speed, so D is selected.

3. In the 100m final at the sports meeting, Zhang Ming lagged behind Wang Liang in the middle, and Zhang Ming accelerated to catch up during the sprint, but they reached the finish line at the same time. Regarding the average speed during the whole process, which of the following statements is correct ( )

A. Zhang Ming’s average speed is greater than Wang Liang’s average speed

B. Zhang Ming’s average speed is smaller than Wang Liang’s average speed

C.The average speed of the two is equal

D. It is not a uniform linear motion and cannot be compared.

[Analysis] Choose C. This question examines the application of average speed. The two people ran the same distance, both 100 m; they started at the same time and reached the finish line at the same time, with the same time. Because the average speed of the whole journey is the same.

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