Biomechanics • Mechanics of movement: – vectors and scalars – velocity, acceleration and momentum/impulse in sprinting – Newton’s Laws applied to movements – application of forces in sporting activities – projectile motion – factors affecting distance, vector components of parabolic flight – angular motion – conservation of angular momentum during flight, moment of inertia and its relationship with angular velocity.

Newton’s Laws What is Newton’s 1st Law? What is Newton’s 2nd Law? Whiteboards- What is Newton’s 1st Law? What is Newton’s 2nd Law? What is Newton’s 3rd Law? Use Newton’s Laws to explain the movement of a sprinter from the start of the race in the blocks, until half way through the race.

Projectile Motion Projectile Motion is the study of the motion of objects moving through the air, such as a rugby ball, shuttlecock or shot put. Understanding projectile motion can help athletes and coaches optimise performance through maximising the distance or accuracy with which they can be thrown or kicked, or anticipating where an object will land. Pgs 88-89

Projectile Motion The flight of an object depends on the following: The size of the action / driving force The mass of the object Air resistance Gravity Once an object has left the hand / foot / racket of the athlete, the action force remains constant. Gravity and the weight of the object also remain constant. Therefore the overriding factor determining an object’s flight path is the air resistance. These two determine the acceleration of the object – why? Newtons 2nd Law- greater force means greater acceleration (proportional) & greater mass equals greater inertia so harder to move.

Recap - Air Resistance When a body or object moves through air (or water) it is subject to fluid friction, which acts in the opposite direction to the motion of the moving body. The amount of air resistance depends upon: The Shape of the object The Size of the object The Speed of the object

Flight Paths Air resistance offered to a projectile whilst in motion may change the parabolic flight path. Flight paths can be categorised in two ways: Parabolic (symmetrical) – this is where the air resistance on an object is negligible so there is no force counteracting the action force Distorted Parabolic (asymmetrical) – this is where the air resistance is large, taking the object away from the normal parabolic flight.

Flight Paths

Shot Put Flight Since air resistance is governed by… the size, shape and speed of an object… … shot put flight is not significantly affected by air resistance. In this case, it is the… Velocity of release Height of release Angle of release that will be the factors that determines the shot put’s flight path. Why not? Air resistance is negligible due to the frontal cross sectional area & shape and surface characteristics of the shot.

Shot Put Flight The initial velocity that any object has can be divided into two components – the horizontal component and the vertical component. Vertical Component Horizontal component Explain why and how the vertical velocity component of a projectile varies during its parabolic flight What force is acting on the shot put during the flight? What does this to do the flight path? Explain why the horizontal component remains constant during the flight path of an object such as the shot put

Rules for drawing shot put flight There are some simple rules that will help you gain full marks on the shot put exam question: The horizontal component remains constant because there is no air resistance The vertical component starts off large, but is zero at the apex (top) of the flight path The vertical component becomes negative after the apex due to gravity The final vertical component is larger than (but opposite to) the initial vertical component The shot put path ends lower than it started – thrown from head height, lands on the ground!

Shot Put Flight Since air resistance is governed by… the size, shape and speed of an object… … shot put flight is not significantly affected by air resistance. In this case, it is the… Velocity of release Height of release Angle of release that will be the factors that determines the shot put’s flight path. Use page 90-92 to summarise how a shot-putter would obtain the optimal flight path, and why each aspect is important

Shuttlecock Flight Explain why the effects of air resistance are much greater on a shuttlecock than on a shot put What effect does the air resistance have on the flight of the shuttlecock? Explain your answer in terms of horizontal and vertical velocity components Sketch the flight path of a shuttlecock. Add approximate vectors for the horizontal and vertical velocity components.