Chapter – 8

Biomechanics and Sports

In this post, we have given the Important Questions of Class 12 Physical Education Chapter 8 (Biomechanics and Sports) in English. These Important Questions are useful for the students who are going to appear in class 12 board exams.

Board	CBSE Board, UP Board, JAC Board, Bihar Board, HBSE Board, UBSE Board, PSEB Board, RBSE Board
Textbook	NCERT
Class	Class 12
Subject	Physical Education
Chapter no.	Chapter 8
Chapter Name	(Biomechanics and Sports)
Category	Class 12 Physical Education Important Questions in English
Medium	English

Very Short Answer Type Questions (1 Mark Each)

Q.1. Define trajectory.
Ans. The flight path followed by a projectile is called it’s trajectory.

Q.2. What do you mean by sport biomechanics?
Ans. Sport biomechanics is the study of forces and stresses of human movements & their effects, atheletics performance and safety.

Q.3. What is Kinesiology.
Ans. Kinesiology is science dealing with interrelation ship of physiology processes & Anatomy of human body with respect to movement.,

Q.4. What do you mean by axis?
Ans. Axis is an imaginary point or line around which the movement take places.

Q.5. Explain Gravity?
Ans. Gravity is the force of attraction exerted by the earth towards it’s centre on a body or an object.

Q.6. What is Air-resistance?
Ans. When a projectile moves through the air, it is slow down by air-resistance.

Or

Air-Resistance is a force which applied by air to object slowdown or fast in the air.

Q.7. Define velocity?
Ans. The distance covered by an object per unit time is called velocity.

Q.8. What is planes in sports?
Ans. Planes is an imaginary, flat surface passing through the body organ.

OR

Plane is a surface on which the movement occurs or take places.

Q.9. What is the law of inertia?
Ans. It is the first law of motion. According to this law. “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 unless & untill acted an external faces on the body.”

Q.10. What do you mean by aerodynamics?
Ans. “Aerodynamics is the study of properties of moving air & the interaction between the air and solid bodies moving through it.”

Q.11. What is weight?
Ans. Weight is the force generated by the gravitational attraction force of the earth?

Q.12. What is left?
Ans. Lift is the force that pushes the objects to move upward.

Q.13. What do you mean by movement?
Ans. Movement is the act or process of moving especially change of place or position or posture.

Q.14. What is angular movement?
Ans. Angular movement occurs only between the long bones. Angular movement, “the angle between the two bones is increased/decreased the movement of body.

Q.15. Define circumduction?
Ans. Movement which takes place between the head of a bone and its articular cavity.

Q.16. What is friction?
Ans. Friction is an invisible force (external force) that opposes the motion of the objects.

Q.17. Write the type of friction?
Ans. Friction is two types.
1. Static friction
2. Dynamics/Kinetic friction
(a) Rolling friction
(b) sliding friction

Q.18. Enlist the muscles involved in running?
Ans. (a) Glutes, (b) Quads, (c) Calves, (d) Hamstrings, (e) core muscles, (f) Biceps.

Short Answer type Questions (3 marks each)

Q.1. Define bio-mechanics? Write its importance is sports.
Ans. Biomechanics is the study of structure & function of biological system of human in relation to movement”.

Or

Bio-mechanics means,” Study of living being’s muscles/ physical activities and the activities of active muscles. Importance of biomechanics in sports.

• Improve performance in sports
• Improvements in technique
• Development of sports equipments.
• Improve in training technique
• Helps in understanding human body.
• Knowledge of safety principles.
• Helps in research work.
• Creates confidence in player.
• Helps in maintaning healthy body.
• Increase the popularity of sports.

Q.2. State the Newton’s law of motion with suitable examples of its application in sports.
Ans. Newton’s Law of Motion and Their Application in Sports

1) First Law of Motion (Law of Inertia)
According to first law of motion “an object rest will remain at rest or an object in motion will remain at motion at constant velocity unless acted by an external force.”
Example : A moving football slows down and then stops often. Sometime. It comes to rest due to the friction between the ground and the ball.

2) Second Law of Motion (The Law of Acceleration)
According to Newton’s second law of motion, “the rate of change of momentum of a body is directly proportional to the impressed force and takes place in the direction of force. F = m.a
Example : A cricket players while catching a ball moves his hands backwards. Initially the ball is moving with a certain velocity. The players has to apply a retarding force to bring the ball to rest in his hands.

3) Third law of Motion (Law of Action And Reaction)
According to the Newton’s third law of motion, “to every action there is always an equal and oppsite reaction.”
Example : The swimmer pushes the water in the backward direction with a certain force. Water pushes the man forwards with an equal and opposite force.

Q.3. What is Friction? Discuss various types of Friction. 
Ans. Friction is the force that combats relative motion between the two surfaces that comes in contact. Friction always acts in the opposite direction of the applied force. Type of frictions :
Static friction : The opposite force that comes into play when one body is actually moving over the surface of another body. Dynamic friction are two types.
Rolling friction : The oppsing force that comes into play when body is actually rolling over the surface of another body. For example, hockey/cricket ball is hit.

Sliding friction : The opposing force that comes into play when one body is actually sliding over the surface of the other body. For example- Ice sketting.

Q.4. What is kinesiology. Write its importance in the field of sports.
Ans. Kineoioloy is the branch of physiology that studies mechanics and Anatomy in relation to human movement”.
Importance of kinesiology in sports.

• To enchance performance of athlete.
• To help to select the athlete’s events.
• Help to select the athlete’s activities & equipment
• To help to develop sound psychology toward the exercises
• To help physiotherepist for testing a person’s range of movement.
• To help of design rules & regulation & facilities
• To evaluate the performance.

Q.5. Differentiation between advantage & disadvantage of friction in the field of sports.
Ans. Friction is usually called necessary evil. It means it is essential in the life and we can not do any work without it.

Advantages of friction

• Keeps the object at position By friction, the objects can be placed at position and shaped.
• Helps to move: Frictional forces helps to move object by friction. It helps in running, walking. With friction of feet/ shoes on the surface, helps to speed. Frictional force helps to move the object in the speed. For example : Spikes are used by the athletes to runf ast.
• Hold or grip an object: with the help of frcitin the ridges of skin of our fingers and our palm enable us to grab and hold objects.
  For example- In badminton the players use grip to hold it.
• Produce heat : The law of conservation of energy states that the amount of energy remain constant. Thus, the energy that is lost due to friction in trying to move and object is really turned into heat energy

Disadvantage of friction

• Wear and tear of object:  Due to friction, there is wear and tear of objects. Lubri cation is used to allow the parts to move easier,moreover, Prevents wear and tear.
• Wastage of Energy: Excess  the of friction means extra  energy, thus energy is being  wasted.
• Slow down the Speed: In the  roller Sketting, Rolling Shoes and smooth surface are used to minimize friction.
• Makes movement difficult:- Friction can make the job more difficult when one has  to move the object. Excess friction can make it difficult to slide a box across the floor, walk through deep snow.

Q.6. Discuss the principles of aerodynmics in brief.
Ans. Aerodynamics is related to the flow of air around a projectile which can influence the speed & direction of the object. But in case of water, water around an object influence the speed & direction of the object is called hydrodynamics.
The Aerodynamics principles are based on:

• Weight: The force of gravity pulling the objective.
• Lift the Air pressure imposed on the object.
• Thrust: It is the forward movements needed by the object to travel.
• Drag: It is the part or surface of the object providing resistance and slowing it down.

Q.7. Differentiate between flexion and extension?
Ans.

• Flexion Movement:- Flexion is an agnular movement in which joints angle of the body’s parts decrease & parts of body come closer together. Ex. bending of lower limb

• Extension Movement:- Extension is and angular movement in which joint’s angle of the body’s parts increase & parts of body move farther (apart) Ex. straightening the lower limb at  the knee

Long Answer Type Questions (5 Marks Each)

Q.1. Write the application of Newton’s Laws motion in sports with suitable examples?
Ans. Application of Newton’s Lows of motion in Sports
Using mechanical principles athletes can build excellent technique. Newton’s Laws of Motion are the foundation for these mechanical principles, which when applied along with other sports training principles renders higher levels of sport performance.
The three laws of newton find application in the following forms in sports :

• Principles from the Law of Inertia
  • Effective combination of linear and angular motions are helpful in achieving dexterous movements. For example, a discus thrower’s body must move in a straight path from the back to the front of the ring while rotating with increasing velocity.
  • When two or more motions are required, athletes must execute movements continuously in sequence. For example, if a javelin thrower hesitates or stops at the end of the approach just prior to the throw, the advantage of the approach is lost.

• Principles from the Law of Acceleration
  • Acceleration is proportional to force applied. For example, a sprinter increases acceleration by increasing the force that he applies against the track.
  • Maximum acceleration can be achieved by coordinating all body forces in the intended direction. For example, a swimmer coordinates the body actions to generate maximum force while minimizing unnecessary movements that cause excessive lateral deviations.

• Principles from the Law of Counterforce
  • Counterforce can be maximized with stable surfaces. If a surface is stable, it offers the same amount of force back as is generated against it. For example, sand does not offer a stable surface for running as compared to a concrete surface.
  • Maximum jumping height can be achieved by pushing directly downward upon take off. The direction of counterforce is directly opposite to that of the applied force and the applied force is most effective when it is perpendicular to the supporting surface.
  • Staying in contact with the ground helps. In activities involving throwing, pushing, pulling or striking, one or both feet should be kept in firm contact with the ground until the force application is complete.

Q.2. What is projectile? Explain the factors affecting project trajectory?
Ans.

Projectile: It is a body in free fall that is subjecFohly to the forces of gravity and air resistance. Any object when thrown or projected into space or air with a force is called a projectile. The primary force acting on a projectile is force of gravity but the force of air resistance also affects the motion or path of projectile.

Projectile motion : It is a form of motion in which an object or projectile is thrown obliquely near the earth’s surface, and it moves along a curved path under the action of gravity only.

Trajectory: The path followed by a projectile motion is called its trajectory or parabola. Projectile motion only occurs when there is one force applied at the beginning of the trajectory, after which there is no force in operation apart from gravity. Some examples of projectiles include :

• A baseball that has been pitched, batted, or thrown.
• A bullet the instant it exits the barrel of a gun or rifle.
• A hammer, javelin or discus once it is released by the athlete.
• A long jumper while performing the jump.

Factors Affecting Projectile Trajectory
The projectile trajectory or object (hammer, javelin, shot, ball, long jumper, diver or an athlete) flight is affected by the
following factors :
1. Angle of projection : It is the initial angle of trajectory relative.to the horizontal. The shape of the projectile motion (trajectory) also depends on the angle of projection because the relative magnitudes of the vertical and horizontal components vary with the angle of the projectile velocity. If angle is perfectly vertical, trajectory also vertical, If angle oblique, trajectory is parabolic, If angle horizontal, trajectory is half parabola. If an object
is projected at the angel of 90° it does not cover any linear distance and falls back on the same spot from where it was projected. To maximize range, optimum angle of landing is always 45°.

 

The parabolic path of an object at different angles
2. Relative height of projection : This is the release height compared to the final landing height of the projectile. When projection speed is constant, greater relative projection height provides longer flight time which increases horizontal displacement. Taller shot putters can throw farther than shorter ones even if throw with same speed.

3. Initial velocity : It is the speed of projection the velocity of the object when it was first released. When projection angle and other factors are constant, projection speed determines the length of trajectory (range), for vertical projectile, speed determines apex, for oblique projectile,
speed determines height of apex and horizontal range.

 

Initial Horizontal Velocity Initial Velocity of a Projectile
4. Air resistance and wind : Particles of the air are to be deflected so that the projectile can move forward, so the projectile applies a force to the fluid (air) particles that moves them along the outside of the system. This applied force tends to resist the motion of the projectile. Hence, the air resistance (or air drag) will tend to affect the velocity of a projectile. It tends to slow down the horizontal component of velocity so that the path of a
projectile (if the initial horizontal component * 0) will tend to have a steeper angle at the end than when the projectile is launched.

5. Gravity : Newton’s law of universal gravitation states that everybody in the universe attracts every other body with a force directed along the line of centers for the two objects that is directly proportional to the square of the separation between the two objects. The force of gravity acts on the body, accelerates it towards center of earth and limits its vertical component. This decreases the upward motion of the projectile by pulling it down towards the earth. If the weight of trajectory is more; gravity affects it more.

Action of gravity

6. Spin : The amount and direction of spin acting on a projectile will directly affect the distance a projectile will travel. The reason for this is the air pressure acting on the ball. A topspin shot creates a region of high pressure on top of the ball, and a region of low pressure below. Air moves from a region of high to low pressure and as a consequence the ball will dip suddenly, decreasing the vertical component of the trajectory and in turn, the distance travelled. In a backspin shot, a region of high pressure is created under the ball, and low pressure above the ball. Air moves from high to low pressure. The air pressure acting on the ball will cause it to stay up longer, increasing the vertical component of the trajectory, therefore increasing the distance travelled. An object propelled without spin tends to waver due to air resistance against an irregular surface, but a small amount of spin produces stability. For example, a volleyball served with a slight spin follows a true course of flight.

Q.3. Discuss the various types of movement in detail?
Ans. Movement is the act of or process of moving especially change of place or position or posture. There are various types of movements in joints which may be divided into four major kinds, i.e., ghding and angular movements, circumduction and rotation and a few other movements.

1. Gliding Movement: Gliding movement is the simplest kind of motion that can take place in a joint, one surface gliding or moving over another without any angular or rotatory movement. Though it is very common to all movable joints, but in most of the articulations of the carpus and tarsus, it is the only motion permitted.

2. Angular Movement: Angular movement occurs only between the long bones. By angular movement, the angle between the two bones is increased or decreased. It may take place forward, backward, flexion, extension, adduction and abduction. Adduction and abduction combined with flexion and extension are met within the more movable joints as in the hip and the shoulder. The various movements which fall under angular movement are described below:

(a) Flexion. Bending parts at a joint so that the angle between them decreases and parts come closer together (bending the lower limb at the knee).
(b) Extension. Straightening parts at a joint so that the angle between them increases and the parts move farther apart (straightening the lower limb at the knee).
(c) Abduction. Moving a part away from the midline (lifting the upper limb horizontally to form a right angle with the side of the body).
(d) Adduction. Moving a part toward the midline (returning the upper limb from the horizontal position to the side of the body).

Q.4. Discuss the major muscles involved in running?
Ans. Major Muscles Involved in Running
There are following major muscles involved in running

1. Glutes. These muscles stabilise your hips and legs. These muscles give extra strength. These muscles work with the hamstring muscles and help hip flexors when your leg retracts behind you preparing to propel forward.

2. Quads. Quads propel you forward and help straighten out the leg in front so that it can make a good contact with the surface of the ground. These muscles are mainly used in the ‘drive’ phase.

3. Calves. These muscles give you spring in your step and at the same time these muscles act as shock absorbers.

4. Hamstrings. As you move forward, the action switches to your hamstrings, the muscles at the back of you thigh muscles. Infact, these muscles help you in pulling the leg back behind your and give you the strength to propel your body forward. They have to lengthen quite a big when you run.

5. Core Muscles. Strong abs and back are really important because they keep you posture upright and overall form good. These muscles play a very sigtnificant role in runing.

6. Biceps. Biceps also play a vital role in running. In fact, biceps maintain a bent arm and help in swinging your arms back and forth while running.

Q.5. Explain the major muscles involved in jumping & throwing.
Ans. Major Muscles Involved in Jumping
Most probably, the leg, feet and gluteus muscle groups are used in jumping. Specific muscles which are involved in jumping are gluteus maximus, hamstrings, quadriceps and soleus. In fact, jumping occurs in three stages.

• The first stage is the preparatory stage where ankle muscles calf muscles and soleus tense to prepare launching.
• The second phase is the launch phase, where hip extensors, the hamstrings and gluteusffraximus combine and the knee extensors extend
  the knees to allow the body to launch into the air.
• In the last stage is the landing phase where all the muscles embrace impact and allow the body to return to a resting position. Core muscles also play a very vital role in jumping. However, the muscles of the arms also help in jumping farther. 

Major Muscles Involved in Throwing

In throwing, the major muscles such as pectoralis, major, latissimus dorsi, anterior deltoid and teres major ar envloved. These muscles are completely responsible for velocity during the throw. The pectoralis major is thelarge muscle in the chest and latissmus dorsi are the large muscles on each side of your back. Deltoid, biceps and triceps are also involved inthrowing shot and javelin in athletics.

Q.6. What do you mean by Axis & Plane? Discuss the type of axis of rotation & planes?
Ans. Introduction to Axes & Planes
Human movements are described in three dimensions based on a series of planes and axis. An axis is a straight line around which an object rotates. Movement at the joint takes place on a plane about an axis. There are three axes of rotation:

1. The Sagittal Axis: The Sagittal axis passes horizontally from posterior to anterior and it is formed by the intersection of the sagittal and transverse planes.

2. The Frontal Axis: The Frontal axis passes horizontally from left to right and it is formed by the intersection of the frontal and transverse planes.

3. The Vertical Axis: The Vertical axis passes vertically from inferior to superior and is formed by the intersection of the sagittal and frontal planes.

There are three planes of motion that pass through the human body.
1. The Sagittal Plane: The Sagittal plane lies vertically and divides the body into right and left parts.
2. The Frontal (coronal) Plane: The Frontal plane also lies vertically and divides the body into anterior and posterior parts.
3. The Transverse (horizontal) Plane: The Transverse plane lies horizontally and divides the body into superior and inferior parts.

When describing anatomical motion, these planes describe the axis along which an action is performed. So by moving through the transverse plane, movement travels from head to toe. For example, if a person jumped directly up and then down, their body would be moving through the transverse plane in the coronal and sagittal planes. There is a tendency when describing a movement for it to be referred to in the particular plane that it is dominated by. An example of this would be a notion of walking as a saggittal plane movement.

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