Everyone asks how to adjust coefficient of friction while you are adjusting shape of racquet and direction of swing so it can be done.
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1. Impact and friction
The closer direction of force is to center of ball, more impact components. If direction of force deviates from center of table tennis ball, friction will be relatively greater. The core of friction is to swing fast..
Second, cause of contention
The force of friction is actually a kind of tangential force. The tangential force is deviation from center of ball and friction against edge of ball, rapid friction against edge of ball, no matter what angle it is at, whether it is pointing up or surface of racket is pressing on top of the ball, quickly wipe with a thin layer.
Third, relationship between friction and impact
(1) What is friction angle
When direction of swing and angle of racquet's surface are determined, it also determines whether there will be more friction or more impact. For example, angle of face of racket is crushed to death. If direction of swing is basically same (also horizontal) as angle of face of racket, there will be more friction when hitting ball at that time. For example, angle of face of a racket is straight (vertical), if direction of swing of racket is from back to front, then a closed angle is formed between them, which can be called angle of friction. The larger angle of friction, more components are affected.
(2) Friction angle adjustment method
1. Change shooting angle
Reducing angle of friction is achieved by changing angle of racket surface. Push racket forward, direction of swing is still forward, and angle will become smaller. Push forward again and angle will continue to decrease. , forming The smaller angle of friction, greater its frictional component.
2. Change rotation direction
Changing direction of swing can also change angle of friction. When angle of racquet is relatively vertical, angle gets smaller as racquet turns up. The smaller angle, more friction it has.
3. Friction and impact adjustment
When hitting ball from back to front, angle of friction is relatively large. In complementary process of friction and impact, it is necessary to change angle of friction and control adjustment of ratio between impact and friction by changing the angle of friction.
There are two ways to change angle of friction: changing shape of racquet and changing direction of swing. These two factors can control angle of friction.
What we talked about today is more complex. You can watch episode "Learning Horizontal Table Tennis Racket for All People" where we specifically talked about mechanical analysis of loop ball. The relationship between angle of friction.
We will stop here today, and in next issue we will talk about center of gravity of body.
Ping-pong network organized by Liu Baosheng
November 28, 2023