Very good for physical education

1. Unit -8
Biomechanics and sports

2. Newtons law
1. Newton’s First Law of Motion Law of inertia – This law states that a
body at rest will remain at rest and a body in motion will remain in
motion at the same speed and in the same direction till any external
force is . applied on it to change that state.
Application in sports: In basketball, players on the court must keep in mind about dribbling because the
ball will continue to bounce for some time if they lose control. If the ball bounces too far away from the
player, his or her team can lose possession.
2. Newton’s Second Law of Motion This law states that the acceleration of an object is directly
proportional to the force producing it and inversely proportional to its mass.
Application in sports: Runners struggle while stopping at the finish line because it requires a very sudden
change in motion. Shot-put throw.
3. Newton’s Third Law of Motion This law states that to every action, there is always an equal and
opposite reaction.
Application in sports While swimming, the swimmer pushes the water backwards using his hands and thus
attains a forward push due to an equal and opposite reaction from the water

3. EQUILIBRIUM: A state of balance or a stable situation, where opposite forces cancel each
other out and where no changes are occurring.

4. CENTRE OF GRAVITY AND ITS APPLICATION IN SPORTS
The centre of gravity moves according to the athlete's body position. For
example, in the runner in the image above, his centre of gravity is in the lower region
of the pelvis and in front of his body, because his upper body is leaning forwards.
CENTRE OF GRAVITY: Centre of gravity is that point in a body or system around which its mass or
weight COG is evenly distributed or balanced and through which the force of gravity acts. The Centre
of gravity is fixed, provided the size and shape of the body do not change.

5. FRICTION
Friction can be defined as the resistance to motion of two moving objects or surfaces
that touch. Friction plays a very important role in many sports, such as bowling and curling.
Static Friction: . Static friction is the friction before an object starts to slide
Kinetic Friction, while Kinetic friction is the friction when the object is actually moving or sliding.
Friction in Sports
Friction plays a big role in rolling sports such as tenpin bowling and curling. In tenpin, the friction
resistance on the ball makes it slow down and also enables the spin on the ball to make it roll in an
arc. The mass and the surface composition of the ball and the amount of oil on the lane will affect the
magnitude of the friction between the bowling ball and bowling lane. The more oil on the lane means
the ball is slow down less and the harder it is for the bowler to send the ball in a curved path.
Air Resistance
Air resistance is also a form of friction, as it describes the resistance between the surface of an object
or person and the air. Air resistance plays a role in many sports in which balls or other objects are
thrown, and in sports in which the person moves through the air such as running and cycling.

6. Projectile
An object thrown into the space either horizontally or at acute angle under the action of gravity is called a
projectile. In the field of games and sport there are many examples of projectiles such as putting the shot, throwing
a hammer, discus, and javelin in athletics.
Two types of Projectile:
Vertical direction Horizontal direction