biomechanics wjec newton's laws 2 - 2013

Biomechanics – Part 2

All will be able to:• Name and define Newton’s 3 Laws of Motion• Apply and explain each Law to in relation to at least 1 sporting example

Learning Outcomes are:

1

2

3

Newton’s Laws of Motion

AccelerationReactionInertia

Newton’s Laws of Motion

• The size and direction of force applied to an object determines the size and direction of acceleration

• A force is needed to change a body’s state of motion

• To every action there is an equal and opposite reaction

• F = Mass x accelertion

Newton’s Laws of Motion

• When a performer runs down a track, that performer generates an muscular force that is applied to the ground

• The greater the force applied to the ground, the greater the acceleration of the performer

• Which law applies here?

Newton’s Laws of Motion

• When a performer kicks a football and applies a force by contracting their muscles, this causes the football to accelerate.

• Which law applies here?

Newton’s Laws of Motion

• The direction and acceleration of the football is proportional to the force applied by the footballer kicking the ball and in which direction the force is applied.

• Which law applies here?

The final stage of an endurance race often involves a sprint finish.05 Using Newton’s Second Law of Motion, explain how an athlete is able to accelerate towards the finish line. (3 marks)

Using ‘Newton’s First’ and ‘Second Laws of Motion’, explain how

the swimmer dives off the starting blocks.

(4 marks)

The final stage of an endurance race often involves a sprint finish.05 Using Newton’s Second Law of Motion, explain how an athlete is able to accelerate towards the finish line. (3 marks)

Using ‘Newton’s First’ and ‘Second Laws of Motion’, explain how

the swimmer dives off the starting blocks.

(4 marks)

Task 2 - Explain how Newton’s 3 Laws of Motion apply to:

A high jumperKicking a ball

SprintingA sprinting start using blocks

Use diagrams as necessary to explain

Task 1 - Can you explain how forces are functioning to:

• Cause something to move

• Change direction

• Accelerate

• Decelerate

2012 – a) Indentify two of Newton’s Laws of Motion and explain how these could be applied to improve performance in a sporting activity of your choice (4)

The following is indicative of the material that might be included in the answer.

•Newton’s First Law states that ‘a body will remain at rest or at a constant velocity in a straight line unless acted upon by an external force’. It means that any object that is not accelerating has no net force acting on it – the forces cancel out. This can be applied to any athlete is stationary or maintaining a constant speed in a fixed direction. For example, a 100m sprinter in the middle phase of the race (constant velocity) or in the blocks (stationary).

•Newton’s Second Law states that ‘the acceleration of a body is proportional to the force causing it, and the acceleration takes place in the direction that the force acts’. The equation used is Force = mass x acceleration. The most common example used is a sprinter accelerating from his/her blocks.

•Newton’s Third Law states that ‘for every action, there is an equal and opposite reaction’. This means that whenever an object exerts a force on another, then it experiences an equal forced exerted back on it in the opposite direction. Reaction forces have many applications within sport including the sprint start, jumping and kicking a ball.

•Candidates will use a range of examples and credit should be given for these. It is impossible to cover all sports within the mark scheme

All will be able to:• Name and define Newton’s 3 Laws of Motion• Apply and explain each Law to in relation to at least 1 sporting example

•Bonus watch……….. http://www.youtube.com/watch?v=Wdm7xwT-vEQ

Learning Outcomes are:

All will be able to:• Define at least 10 key terms for Biomechanics• Explain positive, negative and zero impulse applied to at least 1 sporting example• Explain how to flatten the arc

Learning Outcomes are:

Term DefinitionForceImpulseVelocitySpeedDisplacementAccelerationDecelerationVectorScalarAir resistanceGravityInertiaPositive ImpulseNegative ImpulseZero ImpulseMomentumGround Reaction ForceFootfall

Force – JamieImpulse - JoshuaVelocity - AlexSpeed - BradDisplacement - CharlotteAcceleration - DomDeceleration - MarcusVector - SamScalar - SameedAir resistance - DeclanGravity - MacauleyInertia - KatherinePositive Impulse - JessicaNegative Impulse - ConalZero Impulse - DanielMomentum - BenGround Reaction Force - James

Define the following terms………………..

Force

Displacement

Velocity

Speed

Acceleration

Deceleration

Vector

Scalar

Air resistance

Gravity

Ground Reaction Force

Footfall

Inertia

Momentum

Impulse

Positive Impulse

Negative Impulse

Zero Impulse

Impulse• Force is not applied instantaneously. • Force is applied for a period of time• i.e. tennis ball stays on face of racket for 5-8ms

• Impulse = Force x Time• Also = Change in momentum

– Impulse can be increased by increasing the force applied or increasing the time over which the force is applied.

– http://www.youtube.com/watch?v=lHo9e-fdAbM

Eg studies into sprint start positions:

Impulse Graphs

Impulse Graphs

Impulse Graphs

Impulse Graphs

Types of sprint starts

There are three types of sprint starts:

•Bunch or Bullet start - The toes of the rear foot are approximately level with the heel of the front foot and both feet are placed well back from the starting line.

•Medium start - the knee of the rear leg is placed opposite a point in the front half of the front foot.

•Elongated start - the knee of the rear leg is level with or slightly behind the heel of the front foot.

Research has suggested that a faster start can be achieved if the athlete remains in the blocks for a longer time in order to gain a good starting “impulse”

The best start is the “medium” start

Tennis example:

•Looser strings in a tennis racket will allow the force to be transferred over a longer time creating more “impulse”

•Research involving spiders born in space (NASA research!) found that spiders in space would construct their webs with threads of different diameters making their web more stable. This research would unexpectedly benefit tennis in changing the position of the “sweet spot” on a racket. If the sweet spot is nearer the “toe” of the racket, greater power can also be generated.

•The major difficulty in designing a high-performance tennis racquet arises from the difference between the position of the maximum speed (the toe) and the position of optimum vibration (the sweet spot).

•In a typical older design, the sweet spot is at the geometric centre of the strung area of the racquet. The impact of the ball on the sweet spot causes minimal strain to the player's hand. However, the average player tends to strike the ball farther out toward the toe, and to obtain maximum power on serves, it is necessary to strike the ball as close as possible to the toe. So, performance can be improved by moving the sweet spot outward.

“Flattening the Arc”

• Usually refers to the movement pattern of the arm where the centre of the throw or swing is flattened. A way of increasing accuracy in hitting or throwing. Eg hockey push pass and golf swing.

• FLATTENING THE SWING ARC– Good technique can↑ contact time with a ball during

collision sports • May provide opportunity for ↑ force application in desired

direction (hockey drag flick) • May also provide ↑ accuracy, however usually occurs with

a ↓ in force application

IMPULSE AND ACCURACY

Flattening the arc increases the likelihood of application of force

to object in desired direction of travel by creating a zone of flat

line motion

A more curved arc reduces the likelihood of a

successful outcome by reducing the opportunity for application of force in the intended direction of

travel

IMPULSE AND SPORT

2. DECREASING MOMENTUM• A cricket ball is hit towards a fielder. The fielder

wishes to stop the ball (take momentum back to zero).– Would he apply a large force over a short period of time– Would he apply a small force over a longer period of time.

• Which method is likely to be more successful in catching the ball?

• Therefore in stopping a force we usually increase the time component so we can reduce the peak force!

All will be able to:• Define at least 10 key terms for Biomechanics• Explain positive, negative and zero impulse applied to at least 1 sporting example• Explain the term to flatten the arc applied to hockey skills

•Bonus watch – Ronaldo Tested to the limit - http://www.youtube.com/watch?v=hZqEj-Qyg6U

Learning Outcomes are: