Biomechanics and Sports Notes in English Class 12 Physical Education Chapter-8 Book-1

 

Bio-mechanics 

Studies the individual's body as a machine. 

In this study, the internal and external forces affecting the movement of the body are studied in depth.

Biomechanics is the branch of science that studies the mechanical processes and their functions in the body of living beings. It mainly focuses on understanding the structure of the body, motion, force, energy, and their interactions.

Biomechanical utility

• Improve game performance. 

• Development of medical equipment and techniques.

• Injuries and measures for their prevention.

• in robotics and prosthetic limb manufacturing.

Explain the importance of biomechanics in physical education and sports? 

• Biomechanics helps improve training

• Helps in improving biomechanical devices

• Helps in improving biomechanical technology

• Helps improve injury prevention

• It helps in understanding the human body 

• Helps to improve sports performance  

Newton's Laws of Motion

1. The law of inertia 

2. Law of acceleration 

3. Law of reaction 

1. Law of inertia -

• The law of inertia is known as Newton's first law of motion. 

• This law states that an object maintains its present state of motion unless an external force acts on it

Example 1 

A football is at rest. It will remain at rest until it is kicked (external force).

Example – 2 

A rolling football (in motion) travels a short distance and then slows down or stops (changes in momentum) because of the friction/gravity (external force) between the football and the ground

2. Law of acceleration - 

• The law of acceleration is known as Newton's second law of motion. 

• This law states that the acceleration of an object depends on the force applied on it and its mass.

• The second law of motion is also known as the "law of momentum".

• The rate of acceleration occurring in any object is proportional to the force applied on the object and inversely proportional to its mass.

Acceleration ∝ force/mass, force = mass × acceleration

Example-

1. In cricket, a ball bowled with double force has greater acceleration than a ball bowled with normal force.

2. A javelin thrower needs more force to throw an 800 g javelin than to throw a 600 g javelin.

3. Law of reaction -

• The law of reaction is known as Newton's third law of motion. 

• This law states that a force applied to an object always results in an equal and opposite reaction force.

• In this law of motion for every action there is an equal and opposite reaction.

Example-

1. While swimming, when we push water backwards (action), our body moves forward (reaction).

2. In firing a bullet, the bullet moves forward (action) while the gun pushes backward (reaction).

3. When we walk, we apply backward force by pushing the ground with our feet and the same reaction force is applied by the ground in the forward direction and this enables us to move forward.

Flying of the Rocket:-

When the rocket engine forces gases downward (action), the gases push the rocket upward (reaction).

Shooting a Gun:-

The bullet is thrown forward with a force (action), and the gun experiences a shock backward (reaction).

Floating on water:-

When the swimmer pushes the water backward (action), the water pushes the swimmer forward (reaction).

Driver's step:-

When you step on the ground and apply a force downward (action), the ground gives you a force upward (reaction).

Discuss the principle of balance?

There are two types of balance-

1. Dynamic balancing 

2. Static equilibrium 

1. Dynamic balancing 

The ability of a person or object to maintain stability while in motion is called dynamic balance.

such as bicycling

2. Static equilibrium- 

When a person is in a stable state it is called static balance. 

For example - headstand in yoga

Balance and its use in sports 

1. Wide/Broad Base: The wider the base, the greater the stability in balance.

Example - During a wrestling match, wrestlers stand with their legs wide apart to create a wider base for greater stability and steady balance.

2. Keeping the point of gravity closer to the ground: The closer the center of gravity (CG) is to the ground, the greater the stability. For the former, during a wrestling match, wrestlers lean slightly forward to lower their center of gravity for more stability and steady balance.

3. Body mass (inertia): An athlete with higher body mass (inertia) has more stability than an athlete with lighter body mass (inertia). Example- It is difficult to move a heavier person than a lighter person. This is why competitions are held in different weight categories in sports like wrestling, boxing, judo etc.

4. Center of gravity in the middle of the base: When the center of gravity (CG) is in the middle of the base, stability is greater. When doing gymnastics or cartwheels, keeping the center of gravity in the middle of the base provides more stability.

What is friction? 

Friction is a type of force that is produced when the surfaces of two objects come in contact with each other and either relative motion is taking place or attempting to take place between them. The friction force always acts in the opposite direction of the action.

Explain different types of friction in sports? 

The resistance to motion produced by the contact between two surfaces is called friction.

There are two types of friction.

1. Static Friction - 

When an object starts moving on the surface of another object but the actual motion has not yet started, it is called static friction.

Example- Starting position of running.

2. Dynamic Friction – 

When one object actually starts moving on the surface of another object it is called kinetic friction.

Example: The friction force applied till the ball rolls and stops is the kinetic friction force.

Dynamic friction is also of two types 

Sliding Friction-

When one object actually slides across the surface of another object it is called sliding friction. 

Example: Loading a box onto a vehicle.

Rolling Friction – 

When one object starts rolling on the surface of another object it is called rolling friction.

Example: A ball rolling on the ground after being hit stops due to rolling friction.

What are the advantages and disadvantages of friction?

benefits of friction

1. Maintaining the position of the object: Friction keeps the position and shape of any object stable.

2. Helping in speed: Due to friction we are able to walk and run comfortably. The runner increases the friction to increase the speed, for example, the runner uses spikes.

3. Strengthening the grip: Due to friction, the player is able to hold the object very well with his hands. Badminton players increase friction in rockets to strengthen their grip.

4. Increase in temperature: Friction causes increase in temperature.

Loss of friction

1. Wear and tear of the object: Due to friction, there is always wear and tear of the object, to avoid this we should use oil or lubricant etc. in the objects.

2. Loss of energy: Friction dissipates energy.

3. Reducing speed: In sports like roller skating, friction reduces the speed of the action. For this the surface is made smooth.

4. Making movement difficult: Hard and excessive friction also makes movement difficult.