"Little Parachute" PPT courseware 2

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"Little Parachute" PPT courseware 2

Review the past and learn the new

1. Air can occupy a certain space. Based on this, what characteristics do you think air has?

2. What are the applications of compressed air in daily production and life?

1. Characteristics: Air can be compressed and becomes elastic after compression.

2. Application in production and life:

1. Sprayer; 2. Nail gun for decoration; 3. Hovercraft; 4. Inflatable tent; 5. Car tires, etc.

Learning objectives of this lesson

1. Do you know what the main parts of a parachute are?

2. Be able to comprehensively apply the knowledge you have learned and make your own parachute.

3. Explore the factors that affect the speed of parachute landing through experiments.

Self-study guide one

1. Read pages P49 to 50 of the textbook and think: What are the main parts of a parachute? What are the main materials used to make a toy parachute?

2. Show off the small parachute you made? See who is more successful?

3. What is the principle behind the slow descent of a parachute?

1. A parachute consists of three parts: canopy, parachute rope, and weight.

2. The principle of slow descent of a parachute: During the falling process of the object, it is acted upon by two forces in opposite directions, the gravity of the earth and the air resistance at the same time, so it descends slowly.

Self-study guide 2

Read pages P51-52 of the textbook and think:

1. What are the factors that determine the speed of parachute descent?

2. How to make the parachute stay in the air longer?

Experiment it yourself

1. Show two parachutes with different sizes but the same weight. Is there any difference in the falling time of the objects?

2. For a parachute with the same parachute surface, reduce the mass of the heavy object. Is there any difference in the falling time of the two heavy objects?

The factors that affect the speed of an object falling are:

1. It is related to the weight of the suspended object. The heavier the suspended object, the faster the parachute will fall;

2. It is related to the size of the parachute surface. The larger the umbrella surface, the slower the object will fall.

To make the parachute stay in the air longer, you can increase the area of ​​the parachute and reduce the weight of the parachute itself.

Small information

The parachute of the Shenzhou spacecraft is 1,200 square meters. The parachute is made of more than 1,900 small pieces of cloth connected like fish scales. This kind of umbrella is called a "ring parasail". The umbrella is made of special textile material. It is as thin as a cicada's wing, but it is very strong and can withstand High temperature of 400℃. The entire umbrella spread on the ground is as big as half a football field, but stacked up it is only as big as a handbag and weighs only over 90 kilograms. Lifted from the top of the umbrella, the canopy is more than 30 meters long. With the parachute cord, a parachute is almost 80 meters long. The material of the parachute rope should not be underestimated. Although it is thinner than shoelaces, a thin rope can bear a weight of 300 kilograms. The return capsule of the Shenzhou 5 spacecraft weighs more than 3 tons, and nearly a hundred parachute ropes "pulled" "Living in" the return capsule can be said to be light weight and extremely safe.

The principle of sky lantern lifting into the sky:

1. After the bottom of the sky lantern is heated, the air inside expands due to heat. However, due to the limited volume of the sky lantern, the excess air will escape from the sky lantern, causing the average density of the entire sky lantern to be smaller than the density of the external air. Therefore, the sky lantern can fly into the sky.

2. In addition, humans also invented hot air balloons using the principle of thermal expansion.

summary:

1. The falling object is acted upon by two forces in opposite directions: gravity and air resistance.

2. The larger the windward area of ​​an object, the greater the air resistance. The characteristics of a parachute are its light weight and large surface area, so the object can fall slowly.

3. There are two factors that affect the falling speed of an object: one is the size of the umbrella surface; the other is the weight of the object.

4. Changing the temperature of the gas can change the buoyancy of the object in the air!

Tangqing evaluation

1. What are the parts of a parachute?

2. What are the factors that affect the falling speed of an object?

Keywords: Little Parachute teaching courseware, E-education version fourth grade science PPT courseware download, second volume, fourth grade science slide courseware download, Little Parachute PPT courseware download, .PPT format;

For more information about the "Little Parachute" PPT courseware, please click on the "Little Parachute ppt" tab.

"Little Parachute" PPT courseware:

"Little Parachute" PPT courseware

Looking back and thinking about the questions

1. How many parts does a parachute consist of?

2. What are the material requirements for making a parachute?

3. What factors are related to the speed of parachute descent?

4. The principle of parachute landing

drop..

File Info

Update Time: 2024-09-08

This template belongs to science courseware Fourth-grade science volume 2 of the E-education edition industry PPT template

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