What is the gas in a ping-pong ball? What are the legal ping-pong serves?

Table tennis, the national sport of China, is a popular ball sport in the world, including attack, confrontation and defense. The competition is divided into several types, such as team, singles, doubles, etc. Although a table tennis ball is small, its production process is also very complicated. Please open the following content to learn more!

Contents of this article

1. What is the gas inside the ping-pong ball?

2. What are the legal serves in table tennis?

3. How many players are needed in mixed doubles table tennis?

What is the gas inside a ping pong ball?

The gas inside the ping pong ball is air. There are two types of ping pong balls: seamed ping pong balls and seamless ping pong balls. The two types of ping pong balls are made in different ways. The material used for seamed ping pong balls is celluloid, which is a sulfur-containing chemical. The gas after burning is toxic, so it is best not to smell it too much.

The reason why the gas in the ping-pong ball has a smell is because of celluloid. Celluloid is composed of nitrocellulose (74%), camphor (24%), ethanol and water (2%).

The seamed ping pong ball is usually made by first making a semicircle from a semicircle mold and then merging the two semicircle molds together in a heated state. The manufacturing process is generally divided into the following steps:

1. Separate the raw materials. 2. Extrusion. 3. Grinding. 4. Softening. 5. First forming. 6. Drying. 7. Cutting. 8. Determine the thickness. 9. Bonding. 10. Hot air drying. 11. Determine the weight. 12. First grinding. 13. Drying. 14. Second forming. 15. Second grinding. 16. Inspection and identification. 17. Seal and product.

From the above steps, it can be seen that there is no inflation step in the entire production process of seamed ping-pong balls.

What are the legal serves in table tennis?

1. When serving, the ball should be placed on the palm of the hand not holding the racket, with the palm open and flat. The ball should be stationary, behind the end line of the serving side and above the horizontal plane of the playing surface.

2. The server must throw the ball almost vertically upwards with his hand, without causing the ball to spin, and make the ball rise no less than 16 cm after leaving the palm of the hand not holding the racket.

3. When the ball drops from the highest point of the toss, the server can hit the ball so that the ball first touches his own table area, then passes over or around the net device, and then touches the receiver's table area. In doubles, the ball should touch the right half of the server and the receiver in turn.

4. From the last moment of rest before the toss until the moment of impact, the ball and racket should be above the level of the playing surface.

5. When hitting the ball, the ball should be behind the server's end line, but cannot exceed the part of the server's body farthest from the end line.

6. When serving, the athlete has the responsibility to let the referee or assistant referee see clearly whether he serves in accordance with the rules of legal serving.

How many players are there in mixed doubles table tennis?

1. Mixed doubles table tennis involves 4 players.

2. A competition in which two players from each team take turns to hit the ball in the order specified by the rules. The competition method and rules are basically the same as those for singles, but doubles has special regulations on the order of serving, receiving and hitting the ball.

3. There is a 3 mm wide white line in the center of the table tennis table, called the center line, which divides the table equally into two half areas, left and right.

4. Characteristics of mixed doubles.

5. Judging from the results of previous world championships, the technical level of a country's table tennis doubles always improves along with the improvement of its singles technical level. However, doubles has its own characteristics, and the two best singles players may not necessarily become the most ideal doubles pairing.

6. Doubles pairing requires tacit cooperation between partners, mutual encouragement, and mutual understanding. They should be able to complement each other in terms of technology and jointly exert their strengths.

7. Doubles has special requirements for footwork. Athletes should not hinder their partners' movements and sights while moving, and should also be conducive to their return of the next ball. In doubles, the serve should create conditions for the partner's attack as much as possible. The serve should be mainly for attack and pull. At the same time, athletes must also master good continuous smashing techniques.