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Mechanical principles sg

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Mechanical principles sg

1. 1. Standard Grade PE Mechanical Principles
2. 2. Mechanical Principles <ul><li>The following are some of the mechanical principles that we use in our Standard Grade course :- </li></ul><ul><li>Resistance </li></ul><ul><li>Balance </li></ul><ul><li>Streamlining </li></ul><ul><li>Centre of gravity </li></ul><ul><li>Force/friction </li></ul><ul><li>Transfer of weight </li></ul><ul><li>Levers </li></ul><ul><li>Propulsion </li></ul>
3. 3. Resistance <ul><li>Resistance can be an advantage or a disadvantage. </li></ul><ul><li>Disadvantage - in swimming the water causes resistance and slows you down. </li></ul><ul><li>Advantage - at the end of 100m sprint, air resistance slows the runner down but this is what the runner wants. </li></ul>
4. 4. Transfer of weight <ul><li>In everyday life, when you want to move you have to transfer your weight in the direction you want to move. </li></ul><ul><li>If you want to move to your right, then you push off your left foot and vice versa. </li></ul><ul><li>In different activities you transfer your weight in order to get more distance, more power etc. </li></ul><ul><li>EG - a Badminton player steps forward after playing an overhead clear to try and get more distance on the shot. </li></ul><ul><li>- a discus thrower transfers their weight continually from one foot to the other whilst spinning across the circle before releasing the discus. </li></ul>
5. 5. Propulsion <ul><li>In water based activities such as swimming, life saving and canoeing, movement through the water is called propulsion. </li></ul><ul><li>Propulsion in swimming is caused by using your arms and legs as levers. </li></ul><ul><li>In canoeing, propulsion is caused by the paddle or oar pulling/pushing against the water. </li></ul>
6. 6. Force and Friction <ul><li>Force </li></ul><ul><li>Muscles provide force. </li></ul><ul><li>When muscles contract strongly, the force causes thrust. </li></ul><ul><li>Friction </li></ul><ul><li>Can be an advantage </li></ul><ul><li>Footballers wear studs on their boots to improve the friction between the boots and the ground </li></ul><ul><li>An ice skater wants to reduce the friction between his skates and the ice – that is why the blades are thin and narrow </li></ul>
7. 7. Centre of Gravity <ul><li>Where your centre of gravity is when you are performing skills determines how balanced a position you are in. </li></ul><ul><li>When moving forwards, backwards etc, your centre of gravity constantly moves to stop us from falling over. </li></ul><ul><li>In Gymnastics, when performing a stationary balance, your centre of gravity will be within your base and the wider the base the more stable the balance. </li></ul>
8. 8. Levers <ul><li>There are many levers in our body. </li></ul><ul><li>The muscles in our bodies move our limbs like levers. </li></ul><ul><li>A long lever will give more speed and this in turn will make the ball, shuttle etc travel further. </li></ul><ul><li>Examples of long levers are - a tennis player using a racket and playing with a straight arm to serve the ball fast. </li></ul><ul><li>A gymnast keeps her legs straight during a headspring to increase her speed of movement </li></ul><ul><li>Short levers may be used to bring accuracy and control to various skills or techniques. </li></ul>
9. 9. Streamlining <ul><li>Streamlining is when you put your body into a shape and position to reduce resistance. </li></ul><ul><li>In swimming, the swimmer will try to keep his/her body as straight as possible in the water and part of this is by putting their face in the water instead of keeping their head up. </li></ul><ul><li>In cycling, the cyclist wears specially designed helmets and clothes to make their body position even more streamlined. </li></ul>