CBSE Textbook: Biomechanics & Sports | Physical Education Class 12(XII) - Notes & Model Test Papers - Humanities/Arts PDF Download

 Page 1


265
Physical EDUCATION-XII
UNIT 
VIII
BIOMECHANICS & SPORTS
Overview
 W Newton’s Law of Motion & its application in sports.
 W Types of Levers and their application in Sports.
 W Equilibrium – Dynamic and Static and Centre of Gravity and its applica-
tion in sports
 W Friction and Sports
 W Projectile in Sports
Students will able to
 W Understand Newton’s Law of Motion and its application in sports
 W recognize the concept of Equilibrium and its application in 
sports. 
 W Classify lever and its application in sports. 
 W know about the Centre of Gravity and will be able to apply it in 
sports
 W define Friction and application in sports.
 W understand the concept of Projectile in sports.
THE IMPOSSIBLE KICK
Roberto Carlos’ goal in 1997 defied physics and still impresses scientists today. When 
the famous free-kick happened, physicists from all around the world were baffled 
by the images. That goal was the catalyst for many studies and analyses about 
aerodynamics and the ball’s curve that day at the Stade de Gerland in Lyon.
One of the most famous studies was conducted by four French scientists -- Guillaume 
Dupeux, Anne Le Goff, David Quere, and Christophe Clanet -- and published in the 
New Journal of Physics in September 2010. In this study, the physicists conduct a 
Page 2


265
Physical EDUCATION-XII
UNIT 
VIII
BIOMECHANICS & SPORTS
Overview
 W Newton’s Law of Motion & its application in sports.
 W Types of Levers and their application in Sports.
 W Equilibrium – Dynamic and Static and Centre of Gravity and its applica-
tion in sports
 W Friction and Sports
 W Projectile in Sports
Students will able to
 W Understand Newton’s Law of Motion and its application in sports
 W recognize the concept of Equilibrium and its application in 
sports. 
 W Classify lever and its application in sports. 
 W know about the Centre of Gravity and will be able to apply it in 
sports
 W define Friction and application in sports.
 W understand the concept of Projectile in sports.
THE IMPOSSIBLE KICK
Roberto Carlos’ goal in 1997 defied physics and still impresses scientists today. When 
the famous free-kick happened, physicists from all around the world were baffled 
by the images. That goal was the catalyst for many studies and analyses about 
aerodynamics and the ball’s curve that day at the Stade de Gerland in Lyon.
One of the most famous studies was conducted by four French scientists -- Guillaume 
Dupeux, Anne Le Goff, David Quere, and Christophe Clanet -- and published in the 
New Journal of Physics in September 2010. In this study, the physicists conduct a 
266
Physical EDUCATION-XII
series of experiments and analysis, resulting in an equation that explains the ball’s 
trajectory and all the forces in action at that precise moment.
This is what they wrote.
“The case of soccer, where is twice as small as L, is worth commenting on. The 
ball trajectory can deviate significantly from a circle, provided the shot is long 
enough. Then the trajectory becomes surprising and somehow unpredictable for a 
goalkeeper,”
“This is the way we interpret a famous goal by the Brazilian player Roberto Carlos 
against France in 1997. This free kick was shot from a distance of approximately 
35  metres, that is, comparable to the distance for which we expect this kind 
of unexpected trajectory. Provided that the shot is powerful enough, another 
characteristic of Roberto Carlos’ abilities, the ball trajectory brutally bends towards 
the net, at a velocity still large enough to surprise the keeper.”
Dupeux, Le Goff, Quere, and Clanet conclude that if the correct calculations were 
made, and the distances and forces were repeated, the famous goal could be 
replicated by another player. This, however, is impossible, in the opinion of one of 
Brazil’s most influential physicists. He describes Roberto Carlos’ masterpiece as a 
“football miracle.”
“Although physics explains perfectly the ball’s trajectory, the conditions at that 
moment, such as the power of the kick, the point of impact of Roberto Carlos’ 
foot on the ball, and the distance to the goal, were so rare that we can call that 
a miracle,” says professor Luis Fernando Fontanari of Sao Roberto Carlos Physics 
Institute, a branch of the University of Sao Paulo -- the most respected university in 
the country.
Page 3


265
Physical EDUCATION-XII
UNIT 
VIII
BIOMECHANICS & SPORTS
Overview
 W Newton’s Law of Motion & its application in sports.
 W Types of Levers and their application in Sports.
 W Equilibrium – Dynamic and Static and Centre of Gravity and its applica-
tion in sports
 W Friction and Sports
 W Projectile in Sports
Students will able to
 W Understand Newton’s Law of Motion and its application in sports
 W recognize the concept of Equilibrium and its application in 
sports. 
 W Classify lever and its application in sports. 
 W know about the Centre of Gravity and will be able to apply it in 
sports
 W define Friction and application in sports.
 W understand the concept of Projectile in sports.
THE IMPOSSIBLE KICK
Roberto Carlos’ goal in 1997 defied physics and still impresses scientists today. When 
the famous free-kick happened, physicists from all around the world were baffled 
by the images. That goal was the catalyst for many studies and analyses about 
aerodynamics and the ball’s curve that day at the Stade de Gerland in Lyon.
One of the most famous studies was conducted by four French scientists -- Guillaume 
Dupeux, Anne Le Goff, David Quere, and Christophe Clanet -- and published in the 
New Journal of Physics in September 2010. In this study, the physicists conduct a 
266
Physical EDUCATION-XII
series of experiments and analysis, resulting in an equation that explains the ball’s 
trajectory and all the forces in action at that precise moment.
This is what they wrote.
“The case of soccer, where is twice as small as L, is worth commenting on. The 
ball trajectory can deviate significantly from a circle, provided the shot is long 
enough. Then the trajectory becomes surprising and somehow unpredictable for a 
goalkeeper,”
“This is the way we interpret a famous goal by the Brazilian player Roberto Carlos 
against France in 1997. This free kick was shot from a distance of approximately 
35  metres, that is, comparable to the distance for which we expect this kind 
of unexpected trajectory. Provided that the shot is powerful enough, another 
characteristic of Roberto Carlos’ abilities, the ball trajectory brutally bends towards 
the net, at a velocity still large enough to surprise the keeper.”
Dupeux, Le Goff, Quere, and Clanet conclude that if the correct calculations were 
made, and the distances and forces were repeated, the famous goal could be 
replicated by another player. This, however, is impossible, in the opinion of one of 
Brazil’s most influential physicists. He describes Roberto Carlos’ masterpiece as a 
“football miracle.”
“Although physics explains perfectly the ball’s trajectory, the conditions at that 
moment, such as the power of the kick, the point of impact of Roberto Carlos’ 
foot on the ball, and the distance to the goal, were so rare that we can call that 
a miracle,” says professor Luis Fernando Fontanari of Sao Roberto Carlos Physics 
Institute, a branch of the University of Sao Paulo -- the most respected university in 
the country.
267
Physical EDUCATION-XII
Fontanari is one of the editors of “Physics of Life Reviews” and “Theory in Biosciences,” 
two of the most important scientific journals in the world. He adds that if the ball 
hadn’t stopped in the net, it would have continued in the air, drawing an incredible 
spiral trajectory, as the image above shows.
“I don’t believe we will see something like that happening again,” Fontanari said.
Israeli scientist Erez Garty also theorized about Roberto Carlos’ kick. In a YouTube 
video, he gave a lesson for “physics dummies,” which explains the magic. The 
transcript is as follows
1
:
In 1997, in a game between France and Brazil, a young Brazilian player named 
‘Roberto Carlos set up a 35-meter free-kick. Carlos attempted the seemingly 
impossible with no direct line to the goal. His kick sent the ball flying wide of the 
players, but before going out of bounds, it hooked to the left and soared into the 
goal. According to Newton’s first law of motion, an object will move in the same 
direction and velocity until a force is applied. When Carlos kicked the ball, he gave 
it direction and velocity, but what force made the ball swerve and score one of the 
most magnificent goals in its history?
The trick was in the spin. Carlos placed his kick at the lower right corner of the ball, 
sending it high and to the right and rotating around its axis. The ball started its flight 
in a direct route, with air flowing on both sides and slowing it down. On one side, the 
air moved in the opposite direction to the ball’s spin, causing increased pressure, 
while on the other , the air moved in the same direction as the spin, creating an area 
of lower pressure.
That difference made the ball curve towards the lower pressure zone. This 
phenomenon is called the Magnus effect. This type of kick, often referred to as a 
banana kick, is attempted regularly, and it is one of the elements that makes the 
beautiful game beautiful. But curving the ball with the precision needed to bend 
around the wall and back into the goal is difficult. Too high, and it soars over the 
goal. Too low, and it hits the ground before curving. Too wide, and it never reaches 
the goal.
Not wide enough, and the defenders intercept it. Too slow, and it hooks too early, or 
not at all. Too fast, and it hooks too late. The same physics make it possible to score 
another impossible goal, an unassisted corner kick.
The Magnus effect was first documented by Sir Isaac Newton after noticing it while 
playing a game of tennis back in 1670. It also applies to golf balls, frisbees, and 
Page 4


265
Physical EDUCATION-XII
UNIT 
VIII
BIOMECHANICS & SPORTS
Overview
 W Newton’s Law of Motion & its application in sports.
 W Types of Levers and their application in Sports.
 W Equilibrium – Dynamic and Static and Centre of Gravity and its applica-
tion in sports
 W Friction and Sports
 W Projectile in Sports
Students will able to
 W Understand Newton’s Law of Motion and its application in sports
 W recognize the concept of Equilibrium and its application in 
sports. 
 W Classify lever and its application in sports. 
 W know about the Centre of Gravity and will be able to apply it in 
sports
 W define Friction and application in sports.
 W understand the concept of Projectile in sports.
THE IMPOSSIBLE KICK
Roberto Carlos’ goal in 1997 defied physics and still impresses scientists today. When 
the famous free-kick happened, physicists from all around the world were baffled 
by the images. That goal was the catalyst for many studies and analyses about 
aerodynamics and the ball’s curve that day at the Stade de Gerland in Lyon.
One of the most famous studies was conducted by four French scientists -- Guillaume 
Dupeux, Anne Le Goff, David Quere, and Christophe Clanet -- and published in the 
New Journal of Physics in September 2010. In this study, the physicists conduct a 
266
Physical EDUCATION-XII
series of experiments and analysis, resulting in an equation that explains the ball’s 
trajectory and all the forces in action at that precise moment.
This is what they wrote.
“The case of soccer, where is twice as small as L, is worth commenting on. The 
ball trajectory can deviate significantly from a circle, provided the shot is long 
enough. Then the trajectory becomes surprising and somehow unpredictable for a 
goalkeeper,”
“This is the way we interpret a famous goal by the Brazilian player Roberto Carlos 
against France in 1997. This free kick was shot from a distance of approximately 
35  metres, that is, comparable to the distance for which we expect this kind 
of unexpected trajectory. Provided that the shot is powerful enough, another 
characteristic of Roberto Carlos’ abilities, the ball trajectory brutally bends towards 
the net, at a velocity still large enough to surprise the keeper.”
Dupeux, Le Goff, Quere, and Clanet conclude that if the correct calculations were 
made, and the distances and forces were repeated, the famous goal could be 
replicated by another player. This, however, is impossible, in the opinion of one of 
Brazil’s most influential physicists. He describes Roberto Carlos’ masterpiece as a 
“football miracle.”
“Although physics explains perfectly the ball’s trajectory, the conditions at that 
moment, such as the power of the kick, the point of impact of Roberto Carlos’ 
foot on the ball, and the distance to the goal, were so rare that we can call that 
a miracle,” says professor Luis Fernando Fontanari of Sao Roberto Carlos Physics 
Institute, a branch of the University of Sao Paulo -- the most respected university in 
the country.
267
Physical EDUCATION-XII
Fontanari is one of the editors of “Physics of Life Reviews” and “Theory in Biosciences,” 
two of the most important scientific journals in the world. He adds that if the ball 
hadn’t stopped in the net, it would have continued in the air, drawing an incredible 
spiral trajectory, as the image above shows.
“I don’t believe we will see something like that happening again,” Fontanari said.
Israeli scientist Erez Garty also theorized about Roberto Carlos’ kick. In a YouTube 
video, he gave a lesson for “physics dummies,” which explains the magic. The 
transcript is as follows
1
:
In 1997, in a game between France and Brazil, a young Brazilian player named 
‘Roberto Carlos set up a 35-meter free-kick. Carlos attempted the seemingly 
impossible with no direct line to the goal. His kick sent the ball flying wide of the 
players, but before going out of bounds, it hooked to the left and soared into the 
goal. According to Newton’s first law of motion, an object will move in the same 
direction and velocity until a force is applied. When Carlos kicked the ball, he gave 
it direction and velocity, but what force made the ball swerve and score one of the 
most magnificent goals in its history?
The trick was in the spin. Carlos placed his kick at the lower right corner of the ball, 
sending it high and to the right and rotating around its axis. The ball started its flight 
in a direct route, with air flowing on both sides and slowing it down. On one side, the 
air moved in the opposite direction to the ball’s spin, causing increased pressure, 
while on the other , the air moved in the same direction as the spin, creating an area 
of lower pressure.
That difference made the ball curve towards the lower pressure zone. This 
phenomenon is called the Magnus effect. This type of kick, often referred to as a 
banana kick, is attempted regularly, and it is one of the elements that makes the 
beautiful game beautiful. But curving the ball with the precision needed to bend 
around the wall and back into the goal is difficult. Too high, and it soars over the 
goal. Too low, and it hits the ground before curving. Too wide, and it never reaches 
the goal.
Not wide enough, and the defenders intercept it. Too slow, and it hooks too early, or 
not at all. Too fast, and it hooks too late. The same physics make it possible to score 
another impossible goal, an unassisted corner kick.
The Magnus effect was first documented by Sir Isaac Newton after noticing it while 
playing a game of tennis back in 1670. It also applies to golf balls, frisbees, and 
268
Physical EDUCATION-XII
baseballs. In every case, the same thing happens. The ball’s spin creates a pressure 
differential in the surrounding airflow that curves it in the direction of the spin.
And here’s a question. Could you theoretically kick a ball hard enough to make 
it boomerang all the way around back to you? Sadly, no. Even if the ball didn’t 
disintegrate on impact, or hit any obstacles, as the air slowed it, the angle of its 
deflection would increase, causing it to spiral into smaller and smaller circles until 
finally stopping. And to get that spiral, you’d have to make the ball spin over 15 
times faster than Carlos’s immortal kick.
So, think again
2
Introduction
Biomechanics is the science of movement of a living body, including how muscles, 
bones, tendons, and ligaments work together to produce movement. Biomechanics 
is part of the larger field of kinesiology, explicitly focusing on movement mechanics. 
It is both a primary and applied science, encompassing research and practical use 
of its findings.
Biomechanics includes the structure of bones and muscles and the movement they 
can produce, as well as the mechanics of blood circulation, renal function, and other 
body functions. The American Society of Biomechanics says biomechanics represents 
the broad interplay between mechanics and biological systems.
Biomechanics studies not only the human body but also animals and even extends 
to plants and the mechanical workings of cells.  For example, the biomechanics of 
the squat includes considering the position and/or movement of the feet, hips, 
knees, back, shoulders, and arms.
The biomechanical principle of motion relates to linear motion, velocity, speed, 
acceleration, and momentum. Motion is a movement that results from a force. In any 
physical activity, there are multiple forces and motions occurring. This could include 
angular motion around a joint or the motion of the whole body in various directions. 
The motion or movements of the body are often caused by forces produced by our 
muscles, but this is not always the case. For example, if an opposition player pushes 
you to the ground, the force has come from them and not your muscles.
Motion can be linear, angular, or general. The type of motion is determined by 
the direction of movement. The only type of motion you are asked to understand 
is linear motion. However, to properly apply velocity, speed, acceleration, and 
Page 5


265
Physical EDUCATION-XII
UNIT 
VIII
BIOMECHANICS & SPORTS
Overview
 W Newton’s Law of Motion & its application in sports.
 W Types of Levers and their application in Sports.
 W Equilibrium – Dynamic and Static and Centre of Gravity and its applica-
tion in sports
 W Friction and Sports
 W Projectile in Sports
Students will able to
 W Understand Newton’s Law of Motion and its application in sports
 W recognize the concept of Equilibrium and its application in 
sports. 
 W Classify lever and its application in sports. 
 W know about the Centre of Gravity and will be able to apply it in 
sports
 W define Friction and application in sports.
 W understand the concept of Projectile in sports.
THE IMPOSSIBLE KICK
Roberto Carlos’ goal in 1997 defied physics and still impresses scientists today. When 
the famous free-kick happened, physicists from all around the world were baffled 
by the images. That goal was the catalyst for many studies and analyses about 
aerodynamics and the ball’s curve that day at the Stade de Gerland in Lyon.
One of the most famous studies was conducted by four French scientists -- Guillaume 
Dupeux, Anne Le Goff, David Quere, and Christophe Clanet -- and published in the 
New Journal of Physics in September 2010. In this study, the physicists conduct a 
266
Physical EDUCATION-XII
series of experiments and analysis, resulting in an equation that explains the ball’s 
trajectory and all the forces in action at that precise moment.
This is what they wrote.
“The case of soccer, where is twice as small as L, is worth commenting on. The 
ball trajectory can deviate significantly from a circle, provided the shot is long 
enough. Then the trajectory becomes surprising and somehow unpredictable for a 
goalkeeper,”
“This is the way we interpret a famous goal by the Brazilian player Roberto Carlos 
against France in 1997. This free kick was shot from a distance of approximately 
35  metres, that is, comparable to the distance for which we expect this kind 
of unexpected trajectory. Provided that the shot is powerful enough, another 
characteristic of Roberto Carlos’ abilities, the ball trajectory brutally bends towards 
the net, at a velocity still large enough to surprise the keeper.”
Dupeux, Le Goff, Quere, and Clanet conclude that if the correct calculations were 
made, and the distances and forces were repeated, the famous goal could be 
replicated by another player. This, however, is impossible, in the opinion of one of 
Brazil’s most influential physicists. He describes Roberto Carlos’ masterpiece as a 
“football miracle.”
“Although physics explains perfectly the ball’s trajectory, the conditions at that 
moment, such as the power of the kick, the point of impact of Roberto Carlos’ 
foot on the ball, and the distance to the goal, were so rare that we can call that 
a miracle,” says professor Luis Fernando Fontanari of Sao Roberto Carlos Physics 
Institute, a branch of the University of Sao Paulo -- the most respected university in 
the country.
267
Physical EDUCATION-XII
Fontanari is one of the editors of “Physics of Life Reviews” and “Theory in Biosciences,” 
two of the most important scientific journals in the world. He adds that if the ball 
hadn’t stopped in the net, it would have continued in the air, drawing an incredible 
spiral trajectory, as the image above shows.
“I don’t believe we will see something like that happening again,” Fontanari said.
Israeli scientist Erez Garty also theorized about Roberto Carlos’ kick. In a YouTube 
video, he gave a lesson for “physics dummies,” which explains the magic. The 
transcript is as follows
1
:
In 1997, in a game between France and Brazil, a young Brazilian player named 
‘Roberto Carlos set up a 35-meter free-kick. Carlos attempted the seemingly 
impossible with no direct line to the goal. His kick sent the ball flying wide of the 
players, but before going out of bounds, it hooked to the left and soared into the 
goal. According to Newton’s first law of motion, an object will move in the same 
direction and velocity until a force is applied. When Carlos kicked the ball, he gave 
it direction and velocity, but what force made the ball swerve and score one of the 
most magnificent goals in its history?
The trick was in the spin. Carlos placed his kick at the lower right corner of the ball, 
sending it high and to the right and rotating around its axis. The ball started its flight 
in a direct route, with air flowing on both sides and slowing it down. On one side, the 
air moved in the opposite direction to the ball’s spin, causing increased pressure, 
while on the other , the air moved in the same direction as the spin, creating an area 
of lower pressure.
That difference made the ball curve towards the lower pressure zone. This 
phenomenon is called the Magnus effect. This type of kick, often referred to as a 
banana kick, is attempted regularly, and it is one of the elements that makes the 
beautiful game beautiful. But curving the ball with the precision needed to bend 
around the wall and back into the goal is difficult. Too high, and it soars over the 
goal. Too low, and it hits the ground before curving. Too wide, and it never reaches 
the goal.
Not wide enough, and the defenders intercept it. Too slow, and it hooks too early, or 
not at all. Too fast, and it hooks too late. The same physics make it possible to score 
another impossible goal, an unassisted corner kick.
The Magnus effect was first documented by Sir Isaac Newton after noticing it while 
playing a game of tennis back in 1670. It also applies to golf balls, frisbees, and 
268
Physical EDUCATION-XII
baseballs. In every case, the same thing happens. The ball’s spin creates a pressure 
differential in the surrounding airflow that curves it in the direction of the spin.
And here’s a question. Could you theoretically kick a ball hard enough to make 
it boomerang all the way around back to you? Sadly, no. Even if the ball didn’t 
disintegrate on impact, or hit any obstacles, as the air slowed it, the angle of its 
deflection would increase, causing it to spiral into smaller and smaller circles until 
finally stopping. And to get that spiral, you’d have to make the ball spin over 15 
times faster than Carlos’s immortal kick.
So, think again
2
Introduction
Biomechanics is the science of movement of a living body, including how muscles, 
bones, tendons, and ligaments work together to produce movement. Biomechanics 
is part of the larger field of kinesiology, explicitly focusing on movement mechanics. 
It is both a primary and applied science, encompassing research and practical use 
of its findings.
Biomechanics includes the structure of bones and muscles and the movement they 
can produce, as well as the mechanics of blood circulation, renal function, and other 
body functions. The American Society of Biomechanics says biomechanics represents 
the broad interplay between mechanics and biological systems.
Biomechanics studies not only the human body but also animals and even extends 
to plants and the mechanical workings of cells.  For example, the biomechanics of 
the squat includes considering the position and/or movement of the feet, hips, 
knees, back, shoulders, and arms.
The biomechanical principle of motion relates to linear motion, velocity, speed, 
acceleration, and momentum. Motion is a movement that results from a force. In any 
physical activity, there are multiple forces and motions occurring. This could include 
angular motion around a joint or the motion of the whole body in various directions. 
The motion or movements of the body are often caused by forces produced by our 
muscles, but this is not always the case. For example, if an opposition player pushes 
you to the ground, the force has come from them and not your muscles.
Motion can be linear, angular, or general. The type of motion is determined by 
the direction of movement. The only type of motion you are asked to understand 
is linear motion. However, to properly apply velocity, speed, acceleration, and 
269
Physical EDUCATION-XII
momentum, the other types of motion should also be defined. Angular motion is 
motion in a circular movement around a central point. Essentially every movement 
of your body at a joint is angular. The general motion is a combination of linear 
and angular motion, such as completing the 400m sprint. It, therefore, becomes 
important to know about the laws of motion for a better understanding of motion 
and its application in physical education and Sports. 
8.1 Newton’s Laws of Motion and their Application in Sports
Sir Isaac Newton (1642-1727) was one of the greatest scientists and mathematicians 
that ever lived. Newton came up with three general rules about the movement of 
objects, which are now known as Newton’s Three Laws of Motion.
8.1.1 NEWTON’S FIRST LAW OF MOTION (LAW OF INERTIA)
According to the first law, a body will remain at rest or continue to move at a 
constant velocity unless acted upon by an external (resultant) force. Inertia is the 
resistance of any object to any change in its motion, including a change in direction—
objectives to keep moving in a straight line at a constant speed. 
Application in Sports 
 h If you slide a hockey puck on ice, eventually, it will stop because of 
friction on the ice. It will also stop if it meets something like a player’s 
stick or a goalpost.
3
A skater gliding on ice will continue gliding with the same speed and in the same 
direction unless an external force acts upon the skater.
4