Heading: How do Biomechanical principles influence movement? The study of biomechanics originates from combining two separate disciplines: bio refers to the study of living organisms; mechanics refers to the study of motion and forces. Biomechanical study involves identifying ways of improving performance through 3 main ways: Refining an athletes technique Modifying and developing equipment Decreased risk of injury by improving movement efficiency Heading: Motion Motion is the movement of the body from one position to another Some bodies are inanimate (non-living) such as basketballs, shot puts; whilst other bodies are animate (living) such as golfers, footballers. Motion itself can be divided into 3 categories: Linear Angular General Sub: Linear Motion Linear motion takes place when a body and all parts connected to it travel the same distance in the same direction and at the same speed. Examples: 100m sprint, skii jumper, glide of the wall in swimming. Sub: Angular Motion Also called Rotary motion. Occurs when the body, limb or object moves along a circular (curved) path about a Fixed point. It moves at same time, direction & angle. The fixed point is the axis of rotation Examples sports such as gymnastics, skateboarding, basketball, diving, figure skating, and ballet Sub: General Motion As in everyday life, the majority of sporting skills have an element of both linear motion and angular motion. This is known as general motion. The swimmers arms represent angular motion, while their hips display linear motion as they glide through the water. Sub: Velocity Velocity is equal to displacement divided by time. Displacement is the movement of a body from one location to another in a particular direction, or an as the crow flies measurement. Velocity is used for calculations where the object or person does not move in a straight line. An example is a Javelin throw. Sub: Speed Although the terms speed and velocity are used interchangeably, the two are the same only when the movement is in a straight line. Speed is equal to the distance covered divided by the time taken to cover distance So, if a runner runs 100m in 12 secs Sub: Acceleration Acceleration is the rate at which velocity Acceleration is the rate at which velocity/speed changes in a given amount of time When a person or object is stationary, the velocity is zero. An increase in velocity is referred to as positive acceleration. A decrease is negative acceleration The ability to accelerate depends largely on the speed of muscle contraction, but use of certain biomechanical techniques, such as forward body lean, can improve performance. Sub: Momentum Momentum refers to the quantity of motion that a body possess. I t is a product of mass and velocity. Momentum is expressed as: Momentum = mass x velocity (M = mv) M omentum is an advantage in many sports, especially in contact sports, balance and throwing sports (Don't copy) Example 1 - When two rugby players collide, the athlete with the greater momentum is more likely to be able to get into an advantageous. However, momentum is only one of many factors that will determine success, including: the angle of collision weight of players tackling technique and timing the amount of contact with the ground that affects stability. https://www.youtube.com/watch?v=hTZI-kpppuw More examples Choose one copy Example 2 - A discus with a mass of 2kg and a velocity of 20m/s will have a momentum of 40kg m/s. The faster the object moves or the more mass of the object, the greater the momentum. Example 3 - Catching a tennis ball vs a cricket ball travelling at the same velocity. A cricket ball is more difficult to catch because it has greater mass and therefore momentum. Momemtum Cont.. Summarise: There are numerous instances in sport where bodies generate momentum but they do not travel in a straight line; for example, a diver performing a somersault with a full twist, football kick, discus throw and golf swing. In each of these cases, the body, part of it, or an attachment to it such as a golf club or tennis racquet, is rotating. We call this angular momentum. Angular momentum is the quantity of angular motion in a body or part of a body Angular momentum is affected by: angular velocity For example, the distance we can hit a golf ball is determined by the speed at which we can move the club head. the mass of the object. The greater the mass of the object, the more effort we need to make to increase the angular velocity. Content/writing space Heading: Balance and Stability All sports require athletes to maintain a steady balance and equilibrium. A rchery, require a stationary and balanced. Gymnastics judged on the degree of balance and stability demonstrated, such as the beam in gymnastics. Rugby Wrestling require opponents to disrupt each others balance There are two main types of balances that are evident in sport: S tatic balance: headstands and handstands. Dynamic balance: skiing and surfing Video Dynamic Balance Aj Bear Swiss Ball #1 - https://www.youtube.com/watch?v=8dk4rEozQpY Aj Bear Swiss Ball #2 - https://www.youtube.com/watch?v=zAXXVhl- C3g https://www.youtube.com/watch?v=-IIlYCV0f3o Sub:Centre of Gravity centre of gravity can actually move outside of the physical mass of the body into space. (COG): The centre of gravity of an object is the point at which all the weight is evenly distributed and about which the object is balance. All Athletes are highly skilled in manipulating body position or equipment. Generally an unconscious and automatic response, refined over years of practice. Centre of Gravity High Jump 1:09 3:22 - https://v=RaGUW1d0w8g&list=PLY25nQRyT8xCBEu36zR yrq4R2deeqA2r 8 Where an object has a uniform and consistent shape, such as a tennis ball, the centre of gravity lies directly in the centre of the sphere. Irregular shapes are more difficult to identify; however, an athlete quickly learns to feel. Sub:Line of Gravity Sub:Base of Support The base of support refers to an imaginary area that surrounds the outside edge of the body when it is in contact with a surface. It affects our stability or our ability to control equilibrium. A wide base of support is essential for stability because the centre of gravity is located well within the boundaries. There are many examples where athletes use the base of support to their advantage. The gymnast performing a pirouette has a very narrow base of support and must work hard to ensure that their centre of gravity remains within the base. Wrestlers widen their base of support to prevent their opponents from moving them into a disadvantageous position. Tennis players lower the centre of gravity and widen the base of support in preparation to receive a fast serve. This enhances balance and enables the centre of gravity to be moved in the desired direction more readily. Swimmers on the blocks widen their feet and move the centre of gravity forward to improve their acceleration. Golfers spread their feet to at least the width of their shoulders to enhance balance when they rotate their body during the swing. Write some examples of how an athlete could use the base of support to their advantage? Heading: Fluid Mechanics Fluid can be either a liquid or gas, predominantly this is either done through water or air. Any sport that includes movement, whether of an object or the human body, is subject to the impact of the fluid it moves through. Generally, sports require this movement through the fluid to be as fast and efficient as possible. Video Down Hill Skiing 0:40 1:25 - https://www.youtube.com/watch?v=MFlEUP8bGPQ Sub: Floatation Immersed in water, there are two opposing forces acting on our bodies Gravity is a force pulling the body down Buoyant force is a force pushing up against a body Ar chimedes' Principle - When a body is in water, the body experiences an upward force equal to the weight of water displaced by the body. For an object to float, it needs to displace an amount of water that weighs more than itself. Conversely, if the object displaces a quantity of water that weighs less than itself, it sinks. Hence, wearing a personal flotation device (PFD) increases buoyancy because its size displaces a lot of water with only a minimal increase in weight. Homework Question (Do in you notes book) Outline using examples some Factors that can influence the flotation and buoyant properties of a body in water? Possible Answers Bone = most dense. Muscle = next, similar to water. Fat = least dense People with a greater amount of body fat float better Legs sink first as they are denser and are mainly muscle and bone The lungs when full of air, act like a balloon. Give your body a bigger volume. Flotation devices e.g. life jacket Wetsuit - The thicker the more buoyant E very floating object has a centre of gravity and centre of buoyancy. Centre of buoyancy: is the centre of gravity/weight of a volume of water displaced by an object when it is immersed in that water. A persons centre of weight/gravity can be altered by a change in body type or body position A persons centre of buoyancy can only be altered by a change in body type Sub: Centre of Buoyancy Sub: Fluid Resistance Forces act on us when we attempt to propel ourselves through a fluid environment. (Air or water) These forces include drag force and lift force. Elite athletes understand and use these forces in a way that will benefit the efficiency of their performance. Swimming Video Sub: Drag Drag: is the force that opposes the forward motion of a body or object, reducing its speed or velocity. Drag forces run parallel to flow direction (airflow, water), exerting a force on the body in the direction of the stream. E xample: The swimmers forward motion gradually decreases due to resisting forces applied by the water. Sub: Types of Drag There are 3 types of drag forces surface, form and wave drag. Surface Drag : is a drag force that is determined by the surface material of and object. It is caused by friction between object and the air or water around it. Rougher surface = more drag. Smoother surface = less drag e.g swim suits. Form: (also called form or pressure drag) refers to drag created by the shape and size of a body or object. Objects cause the medium to separate, resulting in pressure differences at their front and rear. The separation causes pockets of high and low pressure to form, resulting in the development of a wake or turbulent region behind the body or object. https://www.youtube.com/watch?v=XkaLsVOrBk0 Wave: This occurs between different fluid types ie water and air. Swimming along the surface of the water creates waves. The larger the waves the more drag. Question What can be done to reduce drag? Shape- If a body or object is streamlined at the front and tapered towards the tail, the fluid through which it is moving experiences less turbulence and this results in less resistance. Bend forward position in cycling Tactics- eg. Distance runners and cyclists follow one another closely where possible. Surface - A smooth surface causes less turbulence, resulting in less drag. Swimming suits Size of frontal area. If the front of a person or object (area making initial contact with the fluid) is large, resistance to forward motion is increased. Sub: The Magnus Effect The Magnus effect: explains why spinning objects such as cricket and golf balls deviate from their normal flight path. Cricket ball or golf ball is bowled or hit into the air, its spinning motion causes a whirlpool of fluid around it that attaches to the object. The three types of spin. Top - Back - Side - Describe what each type of spin does to a ball? (a) Topspin and (b) backspin. The direction of rotation of an object causes pressure differences that affect ball flight. Tennis Video Surface Drag and Swing Bowling (Cricket) Shine one side of a cricket ball while leaving the other rougher. This allows ball to swing during flight as one side of the ball is able to move through the air with less resistance than the other side. The cricket ball experiences a force towards the side of the low pressure causing it to move in that direction. In fact, where pressure differences occur, objects always move from the area of high pressure to low pressure. Cricket Heading: Force FORCE - Is a push or pull applied by one object on another & tends to produce or change the motion of the objects. F orce is measured in Newtons (N) S peed up, slow down, stop or change direction EXTERNAL FORCE from outside the body. Eg gravity, wind, another person INTERNAL FORCE produced by muscles Sub: Newton's Laws of Motion Newtons first law: An object remains at rest or will move at a constant velocity, unless acted upon by an external force. Newtons second law: The acceleration of a body is directly proportional to, and in the same direction as, the force acting on the body. Newtons third law: For every action, there is an equal and opposite reaction Newton's 1st Law - https://www.youtube.com/watch?v=08BFCZJDn9w Newton's 2nd law - https://www.youtube.com/watch?v=qu_P4lbmV_I Newton's 3rd Law - https://www.youtube.com/watch?v=e1lzB36aHD4 Padding - https://www.youtube.com/watch?v=2OReLcCOCN4 Sub: How the body applies force The body produces force through the coordinated contraction of skeletal muscle, resulting in movement of the skeleton; for example, jumping, throwing and running Maximising force is achieved through training in the development of power and strength. In addition, improving movement patterns through technique can increase the force possible. Sub: How the body adsorbs force Forces exerted on the body are absorbed through the joints, which bend or flex in response to the impact. Examples: Activities such as rebounding in basketball, landing in high jump and stopping the bounce while on a trampoline. Cont.. The body also absorbs forces while catching balls or similar objects. Catching a ball can sting if the force of the ball is not absorbed effectively. Force of the ball remains constant, only variable is the distance through which the hands move when catching the ball. Sub: Applying force on an object There are a number of considerations. First, the quantity of force applied to the object is important. The greater the force, the greater is the acceleration of the object. Second, if the mass of an object is increased, more force is needed to move the object the same distance. Third, objects of greater mass require more force to move them than objects of smaller mass. https://www.youtube.com/watch?v=k8krW5z-MO4 Applying force video