Physical Education Class 12 Important Questions Chapter 10 Kinesiology Biomechanics and Sports is part of Physical Education Class 12 Important Questions. Here we have given Physical Education Class 12 Important Questions Chapter 10 Kinesiology, Biomechanics and Sports.
Physical Education Class 12 Important Questions Chapter 10 Kinesiology, Biomechanics and Sports
1 Mark Questions
Question 1.
What is the difference between axis and plane?
Answer:
An axis is an imaginary line about which the body or limb rotates. A plane is an imaginary flat surface along which a movement takes place.
Question 2.
Elucidate projectile motion.
Answer:
It refers to the motion of an object projected into the air at an angle.
Question 3.
An object thrown into space either horizontally or at an acute angle under the action of gravity is called a projectile. Name the two forces which act on a projectile. All India 2017
Answer:
The two forces that act on a projectile are. propelling force and force of gravity.
Question 4.
What is the first law of Newton?
Answer:
This law states that a body at rest will remain at rest and a body in motion will remain ill motion at the same speed and in the same direction till any external force is applied on it to change state.
Question 5.
Explain what is ‘dynamic friction’? (All India 2016)
Answer:
Dynamic friction is the opposing force that comes into play when one body is actually moving over the surface of another body. Dynamic friction may be of two types i.e. sliding friction and rolling friction.
Question 6.
Enlist the methods of reducing friction.
Answer:
Methods of reducing friction are
- Polishing
- Lubrication
- Use of ball bearings
- Streamlining
3 Marks Questions
Question 7.
What is axis? What are its types?
Answer:
An axis is an imaginary line about which the body (or limb) rotates. It can he divided in three parts
- Frontal Horizontal Axis Axis of the body that passes horizontally from side to side at. right angles to the sagittal plane.
- Vertical Axis Axis of the body that passes from head to foot.at right angles to the transverse plane.
- Sagittal Horizontal Axis Axis of the body. that passes from front to rear lying at right angles to the frontal plane.
Question 8.
What do you mean by plane? Explain its types
Answer:
A plane is an imaginary flat surface along which a movement takes place. It can be divided into three parts as follows :
- Sagittal Plane A vertical plane of the body. which passes from front to rear dividing the body into two symmetrical halves.
- Transverse Plane Any horizontal plane of the body which is parallel to the diaphragm; also called the horizontal plane.
- Frontal Plane Plane of the body which passes from side to side at right angles to the sagittal plane; also called the coronal plane.
Question 9.
Enumerate the laws of motion:
Answer:
The three laws of motion are
- Newtons First Law of Motion This law is also known as 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.
- Newtons 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.
\(a=\frac{F}{m} \text { where } a \propto F, a \propto \frac{1}{m}\) - Newtons Third Law of Motion This law states that to every action there is always an equal and opposite reaction. This law describes what happens to a body when it exerts a force on another body.
Question 10.
How Newton’s second law and third law of motion can be applied in sports.
Answer:
Second Laws If a baseball player hits a ball with double the force the rate at which the ball will accelerate (speed up) will be doubled. Football players can slow down stop or reverse the direction of other players depending upon how much force they can generate and in which direction.
Third Law A swimmer propels herself through the water because the water offers enough counter force to oppose the action of her hands pushing allowing her to move. An athlete can jump higher off a solid surface because it opposes his body with as much force as he is able to generate in contrast to sand or another unstable surface.
Question 11.
“Friction is a necessary evil.” Justify your answer with suitable examples from sport. (CBSE Model Question Paper 2015)
Answer:
Friction is usually called a necessary evil. It means that it is essential in games and sports. Without friction we cannot give a better performance in the field of sports.
Examples are spikes used by athletes for running and studs used in football boots of the players. However, friction has disadvantages also. In cycling, there should not be more friction between road and the tyres of the cycle.
5 Marks Questions
Question 12.
Describe different types of movements.
Answer:
Physical activity is made possible by movements and motions. Every movement takes place in one plane and around one axis.
They are categorised by movement type as follows
- Flexion It takes place when the angle decreases between the two bones attached to a joint.
- Extension It takes place when the angle between the two bones attached to a joint increase. Both flexion and extension occur in the sagittal plane about the frontal axis.
- Adduction It is a movement laterally toward the middle of the body.
- Abduction It is a movement laterally away from the middle of the body. Both adduction and abduction occur in the frontal plane about the sagittal axis.
Question 13.
What are the major muscles that we use while we run?
Answer:
Following are the four muscles that we use while we run
(i) Quads (Quadriceps Femoris) Quads are muscle groups of four basic muscles located on our front thighs. They are
- The rectus femoris
- The vastus medialis
- The vastus lateralis
- The vastus intermedius.
Our quads are responsible for moving two of the joints used in running our knee joint and our hip joint. They work together to straighten our knees and bend our hips.
(ii) Quads (Quadriceps Femoris) Our hamstrings are made up of four muscle-parts on the back of your thighs. These are known as
- The semitendinosus
- The semimembranosus
- The biceps femoris
(two parts long head and short head).
These four parts of our hamstrings allow us to flex our knees. The semitendinosus semimembranosus and the long head biceps femoris work together to extend the hips.
(iii) Hip Flexors (Iliopsoas) Our hip flexors (or iliopsoas) like our quads is comprised of a muscle group of two muscles
- The iliacus
- The psoas major
To our right the shortest muscle the iliacus begins on our pelvic crest (the iliac fossa) and stretches over to our thigh bone (femur). The larger of the muscles the psoas major stretches from our T-12 spinal vertebrae to our L-5 spinal vertebrae and there attaches to the femur. These two muscles work together to help our hips flex.
(iv) Calf Muscles Our calf muscles are located on the back of our leg below our knee. Though many anatomists see the calf muscle to be a single muscle (triceps surae) most say that it is a muscle group like our quads and hip flexors. This group consists of two main muscles
- The gastrocnemius
- The soleus
Our calf muscles will allow us to flex our knee and planter flex our ankle. Like our quads our calf muscles can be strengthened by doing squats. Other good strength-building exercises would include calf muscle raises and skipping!
Question 14.
Which muscles are used in jumping?
Answer:
Following muscles are used in jumping
1. Quadriceps The quadriceps rest on the front of thethighs and they have four components: the vastus medial vastus lateral rectus femoris and vastus intermedius. During a jump you perform hip flexion and knee extension which both activate the quadriceps. Hip flexion takes place when you move your thigh toward your stomach; knee extension takes place when you straighten your leg. A squat is a specific exercise that can help you gain more strength in the quads.
2. Hamstrings The hamstrings are opposing muscles to the quadriceps and have an opposite function. You activate your hamstrings through hip extension and knee flexion. Hip extension takes place when you bend your knee and move your heel toward your butt. Hip extension also causes you to work the glutes. From an anatomical standpoint the hamstrings have three parts: the biceps femoris semimembranosus. All parts get activated during the lowering phase and the explosive phase of a jump. A squat works the hamstrings but you can place more emphasis on them by doing a lunge.
3. Hip Flexors The hip flexors run from the lower stomach to the top of the thighs. They consist of the psoas major and iliacus and because of this they are often referred to as the iliopsoas. As the name implies these muscles get activated when you flex your hip in similar fashion to the quads.
Although these muscles are small they are important for explosive motions like sprinting a jumping. A lying leg raise is a good exercise to strengthen the hip flexors.
4. Calves The calyes hav.e two parts the gastrocnemius and soleus. The gastrocnemius has a lateral head and medial head and it is easily seen on the back of the leg right below the knee. The soleus sits anterior or in front of the gastrocnemius-. Both parts function to plantar-flex the foot. This motion occurs when you jump off the ground and point your toes downward.
Jumping rope is a good cardiovascular exercise to train these muscles because of the repetitive hopping you do on your toes. A tuck jump is a good exercise to.work your calves because it is specific to jumping.
Question 15.
Which muscles do we use in throwing?
Answer:
Following are the muscles which are used While throwing anything like ball football etc
- Shoulder Muscles The deltoids are the muscles of your shoulder which play a crucial role in rotating your arm. Always warm up adequately by performing arm circles to avoid injuring your rotator cuff while performing shoulder exercises.
- Triceps Your triceps are located on the back of your upper arm and aid in the process of extending your arm at the elbow. This action helps you release the ball with force and pushlt in the desired direction. To strengthen your triceps efficiently perform exercises such as triceps pushdowns with a rope or pulley and close-grip bench presses.
- Latissimus Dorsi Your latissimus dorsi often referred to as your lats are located on either side of your spine. These large muscles help produce force for throwing and help transfer epergy from your legs to your upper body. Among the best exercises for strengthening your lats are pull upsseated cable rows and bent-over barbell rows.
- Abdominals While many people exercise their abdominal muscles in hopes of attaining a six-pack this muscle group is highly functional as well. A strong core facilitates the transfer of power from your lower body to your upper body enabling your throws to benefit from the strength of your legs. Among the best exercises for your abs are hanging leg raises and Swiss ball crunch.
- Quadriceps The quadriceps is the major muscle group located on the front of your thigh. This large group of muscle tissue helps you power the ball toward your intended target as you step into your throw. Among the most effective exercises for the quadriceps are the barbell step-up barbell lunge and barbell squats which also work your abdominal muscles.
Question 16.
Define trajectory. Describe the factors affecting the trajectory of a projectile. Delhi 2016
Answer:
A trajectory is a path described by a moving object or the path followed by a projectile. Examples are kicking a soccer ball a throw in cricket throwing a hammer etc.
Factors affecting projectile trajectory are
1. Propelling Force The propelling force produces certain effects depending upon its point and direction of application. If the application is directly through the projectiles centre of gravity only linear motion results from the force.
As the projecting force is moved further from the centre of gravity rotatory motion of the object increases at the expense of linear motion.
If the force is below the objects centre of gravity backspin results. Forward spin results when the force is above the centre of gravity. When the force is off centre to the left clockwise spin results and when it is off centre to right counter-clockwise spin occurs.
2. Force of Gravity As soon as contact is broken with a projected object the force of gravity begins to diminish the upward velocity of the object. Finally gravity overcomes the effects of the upward component of the projectile’s motion and the object begins to descend. The factors that determine how soon gravity will cause the object to descend are
- weight (mass) of the object
- amount of force driving it upward
- the effects of air resistance on the object.
3. Effect of Air Resistance As the speed of an object increases air resistance has a greater retarding effect. The more surface area an object presents in the direction of movement the greater will be the effect of air resistance.
Question 17.
Elucidate the types of friction.
Answer:
The force acting along two surfaces in cozntact which opposes the motion of one body over the other is called the force of friction. It is very important in sports. The larger the area of contact between the surfaces the greater is the force of friction. When both the surfaces are smooth the force of friction reduces to almost zero.
Two types of friction are
- Static Friction The opposing force that comes into play when one body tends to move over another surface but the actual motion has not yet started.
- Dynamic Friction It is the friction between two surfaces that are in relative motion with respect to each other. It is the opposing force that comes into play when one body is actually moving over the surface of another body. Dynamic friction may be of two types i.e. sliding friction and rolling friction.
Question 18.
What is friction? Is it advantageous and disadvantageous in the field of games and sports? All Indio 2017
Answer:
Friction is the force acting along two surfaces in contact which opposes the motion of one body over the other. It has very importance in sports. For example when a cricket ball or hockey ball is hit it moves very fast in the direction of force in the ground. After sometimes its motion becomes less and ultimately it comes in static position.
Advantages
Friction has a great significance in the field of sports. Many sports require more friction and other need lesser friction. In some sports we can not give a better performance without friction. For example in athletics the shoes are designed to increase friction so that better speed can be generated.
The spikes have small nails to crease the friction. Gymnasts sometimes use lime on their palms to perform on horizontal bar uneven bars to increase friction. In these sports friction is necessary thus regarded as advantageous.
Disadvantages
On the other hand some games do not require friction. For example the games like snow skiing the skiis are designed to have minimum friction. In cycling there should not be more friction between road and tyres of the cycle. Thus the tyre should be fully inflated to reduce the force of friction. If there is more friction it will be more wastage of energy of the cyclist. Moreover the cyclists use pointed helmets silk body fitted costume and bend their bodies while cycling to reduce air friction.
Swimmers use goggles cap and full body swimsuit to reduce the force of friction caused by water. In roller skating less friction is also needed for better performance. Thus in these games friction is regarded as disadvantageous.
1 Mark Questions
Question.1. Elaborate the term Biomechanics.
Answer. Biomechanics is the science that examines the internal and external forces acting on a human body and the effects produced by these forces.
Question.2. Elucidate projectile motion.
Answer. When a body is thrown at a certain angle with a certain amount of force into the air, it travels in the air and covers some distance following a curved path called a parabola. This is called projectile motion.
Question.3. Define linear motion.
Answer. Linear motion occurs when all the parts of a body move the same distance in the same direction in the same time. The term linear refers to a straight line.
Question.4. Give one most important mechanical difference between walking and running.
Answer. The body is totally airborne for a period of time during running, whereas at least one foot contacts the ground for the whole cycle during walking.
Question.5. Enlist the methods of reducing friction.
Answer. Methods of reducing friction are
- Polishing surfaces in contact
- Lubrication
- Use of ball bearings
- Streamlining
- Changing the type of material used
3 Marks Questions
Question.6. Write the formula for calculating work, energy and power?
Answer.
Question.7. What do you mean by work? If a person applies a force of 10 pounds to an object and displaces it 21 feet, calculate the work done.
Answer. Work is defined as the product of force and the distance through which the object moves in the direction of application of the force.
Applied force = 10 pounds
Displacement = 21 feet Work = Force x Displacement Work = 10 x 21 = 210 ft -lb
Question.8. What is power? What will be the units of power expressed using foot, pound and second? If a weightlifter does 1500 ft-lb of work in raising a barbell overhead and does it for 5 seconds, calculate the power applied by the athlete.
Answer. Power is the rate of doing work or the rate of energy expenditure.
Question.9. Briefly explain at which angle we throw an object to cover the maximum distance.
Answer. Projectile motion refers to the motion of an object projected into the air at an angle. A few examples of this include a soccer ball being kicked, a baseball being thrown or an athlete long jumping.
For covering maximum horizontal distance the thrower must ideally throw the implement at 45° at maximum velocity. However, this angle is generally less than 45° actually depending on the weight of the implement.
Question.10. Enumerate the laws of motion.
Answer. The three Laws of Motion are
- Newton’s First Law of Motion This law is also known as 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.
- Newton’s Second Law of Motion This law states that the acceleration of an object is directly proportional tathe force producing it and inversely proportional to its mass.
- Newton’s Third Law of Motion This law states that to every action, there is always an equal and opposite reaction.
Question.11. Explain why the angles of release for shot put, javelin and discus throw are different?
Answer. To achieve maximum distance for any of these events, the athlete will have to balance three components – speed, technique and strength. As the angle of release increases, the athlete must expend more energy in overcoming the weight of the object thrown and so less effort is available to develop the release speed of the object. Further, the structure of the body favours a throw in the horizontal direction. As the three objects are differing in weight, the athlete expends different amounts of energy in overcoming their weight. Accordingly, the athlete will release the javelin at a smaller angle of release than the shot put, as the javelin is lighter. The same reason holds for the discus.
Question.12. “Friction is a necessary evil ”. Justify your answer with suitable examples from sport.
Answer. Friction is usually called a necessary evil. It means that it is essential in games and sports. Without friction, we cannot give a better performance in the field of sports. Examples are spikes used by athletes for running and studs used in football boots of the players. However, friction has disadvantages also. In cycling, there should not be more friction between road and the tyres of the cycle.
Question.13. Explain the functioning of Levers.
Answer. The functioning of a lever is characterised by three main parts. These are
- The Fulcrum It is the point at which the lever rotates or turns and which identifies the lever class by its position in relation to the other two parts. In human movement, the fulcrum is the joint which dictates the kind of action.
- The Force Arm It is the point at which the force is applied.
- The Load / Resistance Arm It is the point where the load or resistance is located.
5 Marks Questions
Question.14. Describe the factors affecting the trajectory of a projectile.
Answer. Factors affecting projectile trajectory are
- Propelling Force The propelling force produces certain effects depending upon its point and direction of application. If the application is directly through the projectile’s centre of gravity, only linear motion results from the force. As the projecting force is moved further from the centre of gravity, rotatory motion of the object increases at the expense of linear motion. If the force is below the object’s centre of gravity, backspin results. Forward spin results when the force is above the centre of gravity. When the force is off centre to the left, clockwise spin results and when it is off centre to right, counter clockwise spin occurs.
- Force of Gravity As soon as contact is broken with a projected object, the force of gravity begins to diminish the upward velocity of the object. Finally, gravity overcomes the effects of the upward component of the projectile’s motion and the object begins to descend. The factors that determine how soon gravity will cause the object to descend are
(a) weight (mass) of the object
(b) amount of force driving it upward
(c) the effect of air resistance on the object. - Effect of Air Resistance As the speed of an object increases, air resistance has a greater retarding effect. The more surface area an object presents in the direction of movement, the greater will be the effect of air resistance.
Question.15. Mechanically analyse an athlete walking on the road.
Answer. Walking can be studied in two phases, called as stance phase and swing phase. It proceeds as given below
- Heel Strike This stage starts the stance phase. It begins when the heel first touches the ground and continues until the complete foot is on the ground.
- Early Flat Foot It starts from the moment when the complete foot is on the ground. It occurs when the body’s centre of gravity passes over the top of the toe. The main purpose is to allow the foot to act as a shock absorber.
- Late Flat Foot This stage starts when the body’s Centre of Gravity passes in front of the neutral position. This stage lasts till when the heel lifts off the ground.
- Heel Rise This stage starts when the heel begins to leave the ground. In this stage, the ground forces that go through the foot are very significant.
- Toe Off This stage begins when the toes leave the ground completely. This stage continues until the beginning of the swing phase.
- Swing Phase This stage starts when one foot is on the ground and the other one in the air. This is shorter than the stance phase.
Question.16. Elucidate the types of friction.
Answer. The force acting along two surfaces in contact which opposes the motion of one body over the other is called the force of friction. It is very important in sports. The larger the area of contact between the surfaces, the greater is the force of friction. When both the surfaces are smooth, the force of friction reduces to almost zero.
Three types of friction are:
- Static Friction The opposing force that comes into play when one body tends to move over the another surface but the actual motion has not yet started.
- Limiting Friction Limiting friction is the maximum opposing force that comes into play when one body is just on the verge of moving over the surface of another body.
- Kinetic Friction Kinetic friction is the opposing force that comes into play when one body is actually moving over the surface of another body.
Question.17. Describe linear and angular motion with their characteristics.
Answer. Linear Motion This occurs when all the parts of a body move the same distance in the same direction in the same time. The term linear refers to straight line motion of a body from one point to another point.
Straight line is defined as the shortest distance between two points.
It can take place in two ways :
- Going Straight (Rectilinear) Covering a straight distance.
- Going in a Curved Path (Curvilinear) It is possible for a body to move along a curved path and still satisfy the conditions of linear motion.
Angular Motion Also known as rotation, rotatory motion or circular motion. This occurs when a body moves on a circular path about a central line so that all parts of the body move through the same angle in the same direction in the same time.
The central line which lies at right angles to the plane of motion is known as the axis of rotation. It may be physical or imaginary. It also may be inside or outside the body.
Question.18. Discuss the mechanical analysis of Running.
Answer. Running is an important skill in almost every sports event. The mechanics of running are similar in several respects to those of walking. The most notable factors differentiating a run from a walk is the period of double support, which is not present in running.
Running has the following phases:
- Swing Phase The swing phase begins with the toe off the ground and ends with the foot landing. Since the body moves faster in running, the leg should move forward with more speed. It is flexed considerably more as compared to walking. The leg’s weight is brought closer to the hip, since the lever is shortened by flexion of the knee, reducing the moment of inertia and increasing the angular velocity.
- Support Phase The foot strikes the ground under the knee and under the centre of gravity. The leg strikes the ground with the ball of the foot. During the propulsive action, the vertical components should be kept as small as possible, being just enough to counteract gravity’s downward pulj-so that a great proportion of the force can be used effectively in driving the body forward , rather than be wasted in producing a bouncing run.
Arms swing must be co-ordinated with the legs to keep the balance of the rotatory effect of the leg swing on the trunk. Since the legs are moving faster, the arms must move faster.
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