Presentation on theme: "Year 11 Biomechanics The study of forces and their effects on the human body."— Presentation transcript:
Year 11 Biomechanics The study of forces and their effects on the human body
Characteristics of motion Linear motion - Motion that occurs is a straight line. All parts of the body move in the same direction and at the same speed (e.g. jumping up in the air to catch a ball or travelling in a car). Line out jumper in Rugby Union Drag Racing
Characteristics of motion Angular motion - Motion that occurs around an axis. This axis can be internal (e.g. body parts rotating around a joint) or external (e.g. spinning a ball on your finger). Spinning a ball on your finger Spinning figure skater
Characteristics of motion General Motion - A combination of linear and angular motion. This is the most common of all movements, as most human movement requires the rotation of body parts around joints (e.g. cycling, swimming and running).
Characteristics of motion Apply your knowledge! - Classify the following physical activities as linear motion or angular motion or general motion. 1. Sprinting 2. Rebounding a basketball 3. Driving a car 4. Tossing a underhand ball in basketball 5. Horse riding 6. Lawn bowls
Check your answers 1. Sprinting – General 2. Rebounding a basketball - Linear 3. Driving a car - Linear 4. Tossing a underhand ball in basketball - Angular 5. Horse riding - Linear 6. Lawn bowls - Angular
Balance and Stability Balance and Stability is important during sporting performances. Being stable allows you to put more force into a movement and complete the movement with control
Centre of gravity Centre of gravity can be defined as the single point at which all parts of an object are equally balanced. For a normal human being standing upright, their centre of gravity lies around the area of their navel. A persons centre of gravity can change depending on their body position because as mentioned before, the centre of gravity is the exact point where all parts of an object are equally balanced. The centre of gravity can also lie outside an object, especially if the object is bent over or leaning in a certain direction
Centre of gravity (C.O.G) = Centre of gravity Centre of gravity for a normal person
Centre of gravity Centre of gravity for a person whose hands a stretched in the air = Centre of gravity
Centre of gravity (C.O.G) Centre of gravity outside of a persons body = Centre of gravity
Box Method How can we measure C.O.G? Answer: We use the Box method 1. Draw a box around an image 2. From opposite corners draw a line, until an X is formed 3. Where the lines cross is the C.O.G. Example C.O.G
Line of gravity - The line of gravity is important when determining the stability of an object. Line of gravity is the vertical line that passes through the centre of gravity to the ground. If the line of gravity falls within the objects base of support (i.e. its contact with the ground), the object is relatively stable. If the line of gravity falls outside the objects base of support (i.e. its contact with the ground), the object is relatively unstable.
Line of gravity Centre of gravity STABLE Centre of gravity UNSTABLE Line of gravity
Base of support – The object on the left is more stable because of its relatively larger BOS BOS is the area within an objects point of contact with the ground. The larger the area the base of support covers, the more stable an object will be. Wide BOS Narrow BOS BOS
Line of gravity, BOS in relation to movement The line of gravity (LOG) must go outside the base of support to initiate or continue movement. The direction that the line of gravity takes relative to the BOS will be the direction of the resulting movement. The further away the LOG is from the BOS, the greater the tendency the body has to move in that direction. E.g. Evasive running. Line of gravity Leg pushes against the ground Top of body moves towards LOG Direction of movement Base of support
Centre of gravity, Line of gravity, Base of support and Physical activity Apply your knowledge! - Label the following images with the COG, LOG and BOS. - Is the performer stable?
Centre of gravity, Line of gravity, Base of support and Physical activity