"Speed ​​of Movement" Mechanical Movement PPT

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"Speed ​​of Movement" Mechanical Movement PPT

Part One: Basic Knowledge

1. Two ways to compare exercise speed

1. In the same time, compared with the objects _____________, the object _____________ moves faster.

2. Within the same distance, compared with the object _____________, the object _____________ moves faster.

2. Speed

1. Concept.

Distance and time_____________.

2. Formula. _____________.

3. Meaning.

The physical quantity that represents the movement of an object _____________ is numerically equal to the _____________ that the object passes through within _____________.

4. Unit.

(1)International unit:____________.

(2) Commonly used units:_____________.

(3)Relationship:_____________.

3. Types of exercise

1. Divide according to movement routes.

(1) Straight-line motion: The motion route is ________ motion.

(2) Curved motion: The motion route is _______ motion.

2. In linear motion, the speed changes in minutes.

(1) Uniform linear motion.

①Concept: linear motion of ______________.

② Uniform linear motion is mechanical motion of ______________.

(2) Variable speed linear motion.

①Concept: linear motion of ______________.

②The calculation formula of average speed:_______.

PPT on the speed of movement, part 2: classroom exploration

1. Understanding of speed

1. "Speed" is defined as the ratio of distance to time. That is to say, speed is actually defined by the ratio of two physical quantities: distance and time. In this way, the ratio of two physical quantities is used to define the third physical quantity. The method is called the ratio definition method.

2. The calculation formula of speed is

The two deformation formulas are s=vt and t= s/v. When applying the formula, please note: the three physical quantities must correspond to the same motion process of the same object; the units of each physical quantity in the operation must be unified.

3. Comparison of the speed of uniform linear motion and the average speed of variable speed linear motion.

4. For an object moving at a uniform speed in a straight line, the speed v is a certain value. According to the speed calculation formula v=s/v, it cannot be considered that the speed v of an object moving at a uniform speed is directly proportional to the distance s, and the speed v is inversely proportional to the time t.

2. Use images to describe movement

1.s-t image (as shown in the figure).

The abscissa represents time, the ordinate represents distance, and the image represents how the object's distance changes with time. When the image is an inclined straight line, it means that the object is moving in a straight line at a uniform speed. The greater the inclination of the straight line, the greater the speed of the object. As shown in the figure, both A and B move in a straight line with uniform speed, and A's speed is greater than B's speed.

2.v-t image (as shown in the figure).

The abscissa represents time, the ordinate represents speed, and the image represents how the speed of an object's movement changes with time. If the image is a straight line parallel to the time axis, as shown in Figure A, it means that the object is moving at a constant speed; if it is not a straight line parallel to the time axis, as shown in Figure B, it means that the object is moving at variable speeds.

PPT on the speed of movement, part 3: classroom practice

1. Two ways to compare exercise speed

1. As shown in the picture, the way to compare the speed of two people in picture A is _______________; the way to compare the speed of two people in picture B is _______.

From the question picture A, we can see that the time is the same. Comparing the distance traveled by two people, according to v=s/t, the time is constant, and the longer the distance, the greater the speed; from the question picture B, we can see that the distance is constant, according to v= s/t, time and speed are inversely proportional, the less time, the greater the speed.

Same time compared to distance. Same distance compared to time.

2. Please connect the following objects with their moving speeds correctly.

2. Speed

3. When describing the length of the railway from Shanghai to Beijing, ______________ (optional "kilometer", "centimeter" or "micron") should be used as the more appropriate unit. my country's high-speed rail construction is developing rapidly. If a high-speed train travels at a speed of 100 m/s, the distance traveled by this train in 10 s is _______________m.

This question examines the related calculations of speed. Since the distance from Shanghai to Beijing is relatively long, the unit of length should be selected in a larger unit, that is, kilometers. The distance traveled by the train is s=vt=100 m/s×10 s=1 000 m.

4. Xiao Cong’s family went to Beijing for a trip. At the intersection of suburban roads in Beijing, he saw the traffic sign as shown in the picture. The number “40” on the sign means ____________________________; on the premise of obeying the traffic rules Get off, from this sign to Beijing, it will take _______h at the fastest.

3. Types of exercise

5. The stroboscopic photos of two small balls taken by the same camera are as shown in the figure. Regarding the motion of two small balls, which of the following statements is correct ()

A. Ball A moves for a long time, and Ball A moves in a straight line with variable speeds.

B. Ball A moves for a long time, and Ball A moves in a straight line at a constant speed

C. Ball B moves for a long time, and Ball B moves in a straight line with variable speed.

D. Ball B moves for a long time, and Ball B moves in a straight line at a constant speed

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Update Time: 2024-11-21

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 1 industry PPT template

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