1.
Linear motion – straight or curved line. Motion along a line. All parts same speed / direction.
2.
3.
General motion – combination of linear and angular motion

1.
Pure linear motion
2.
Pure angular motion
3.
General motion
You need to be able to explain why they are each type of motion

If a body changes direction or speed, a force has been applied



Can it move something that is still to move?
E.G.,

A.
Cause a body at rest to move
B.
Cause a moving body to change direction, accelerate or decelerate
C.
Change an object’s shape.

Effect of force
A force can cause a body at rest to move
A force can cause a moving body to change direction
Example:
F exerted by foot – moves the ball from rest
F exerted by GK hands redirects the ball
A force can cause a moving body to accelerate
More F into kick = greater acceleration of the ball
A force can cause a moving body to decelerate
Wind resistance decelerates the ball
GK hands decelerates the ball
A force can cause a body to change its shape
Ball out of shape on kick / foot contact

Effect of force
A force can cause a body at rest to move
Example:
F by leg muscles to move the ‘returner’ into position
A force can cause a moving body to change direction
Force of racket (body muscles) will be exerted onto ball and send ball in new direction (direction on the F applied)
A force can cause a moving body to accelerate
Greater muscular F exerted via racket to ball = greater acceleration of ball to server (lighter ball = greater acceleration too).
A force can cause a moving body to decelerate
Wind in opposing direction decelerates ball.
Resistance, so decelerates ball (gives more time before contact)
Time in air = greater gravitational deceleration
A force can cause a body to change its shape
Racket contact with ball – ball warped (and racket)

Effect of force Example:
A force can cause a body at rest to move
Unless net (unbalanced) F acts, sprinters will stay in blocks
– still
A force can cause a moving body to change direction
F from muscles and arms, pushes on blocks (N3L) and pushes sprinter to change direction out of blocks.
A force can cause a moving body to accelerate
Greater F – Quicker start time out of blocks and acceleration down track
A force can cause a moving body to decelerate
Greater wind resistance decelerates the sprinter
A force can cause a body to change its shape
Air resistance – sprinters cheeks!
Drive from blocks – footwear and foot flatten / expand with F application


Size of the force

Direction of the force

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Without forces being applied, there will be no change in motion!

Whether still of moving.

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

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This is the law of inertia, and states:

‘Everybody at rest, or moving with constant velocity in a straight line, will continue in that state unless acted upon by an external force exerted upon it’

Objects tend to remain either at rest or in straight line motion.

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In simple terms , to change the motion of an object or performer a force must be applied.

A golf ball will only move from the tee when a force is applied to it from the golf club
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A sprinter will only move out of the blocks when they exert force from their muscles


This is the law of acceleration, and states:

‘The acceleration of a body is proportional to the force causing it and the acceleration takes place in the direction in which the force acts’

This law describes the relationship between net force, acceleration, and mass

Often described as:

 This law suggests that the greater the mass of an object, the greater the force required to give the same amount of acceleration and also the greater the force applied the greater the acceleration

For example, less force is applied to the shuttlecock than to a shot put in order for it to move

F - ma


At a constant velocity the force of tire friction (F force of air resistance
(F
2
1
) and the
) have a vector sum that equals the force applied by the cyclist (Fa).

The net force is therefore 0.


More mass results in less acceleration when the same force is applied.

With the same force applied, the riders and the bike with twice as much mass will have half the acceleration, with all other factors constant.

Note that the second rider is not pedaling.

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One person is to use the bats and balls to devise a sporting example to explain how mass and acceleration affect each other.

Those taking part can only agree or disagree.
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If you do disagree you take over as the teacher.

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Are you able to do the same for the third Law?
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Those taking part can only agree or disagree.

If you do disagree you take over as the teacher.

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This is the law of reaction, and states:

‘ To every action there is an equal and opposite reaction’

When a swimmer for example exerts a force on the starting blocks, the blocks exert an equal and opposite reaction force upon the swimmer, propelling them into the pool


The American football player's foot is pushing against the ground, but it is the ground pushing against the foot that accelerates the player forward to catch a pass.

1st Law – INERTIA - remains at set unless a force affects them
2nd Law – ACCELERATION - push harder to get more acceleration
3rd Law – ACTION & REACTION - action force is muscular force, reaction force pushes athlete off blocks


Draw a free flow diagram using Newton's laws of motion to describe the resultant forces impacting on the ball.

If you agree with what is being drawn then allow them to continue.

If you disagree then you take over.

 The amount of material of which it is made.
 Shot put vs foam ball
 Used to advantage in sports?


The point at which the body is balanced in all directions


Distribution of mass – symmetrical

Body position and shape – unsymmetrical; males vs females

Changing positions – HJ (Western Roll vs
Fosbury Flop


With a partner one of you stand with your back against a wall. Your heels against the wall

Try and place a ball down on the floor without moving your feet.

See if your partner can place the ball further away?


Why do you fall forwards?
Or if you don’t fall why do you feel like falling?


Distribution of weight around a balance point

The centre of a body's mass. In the human body it is the point, which all parts are in balance with one another.

It is dependant on current position in space, anatomical structure, gender.




Is determined by :

Position of athlete’s centre of mass

Position of the athlete’s line of gravity= a line extending from the centre of mass vertically down to the ground.

Size of the athlete’s area of support





Adopt a wide stance arms down
Adopt a wide stance arms up
Feet together arms down
Feet together arms up

Is there a difference in how easy it was to move the person?


We talked about angular and linear motion at the beginning of the class, so how can we create these types of motions?



Investigate how you can cause these actions using the tennis ball.
Think about the force that you are applying and the centre of mass.


Linear motion – force passes through the centre of mass DIRECT FORCE

Angular motion – force passes outside the centre of mass ECCENTRIC FORCE

Application of
F
Type of F
F passes through the
C of M
DIRECT
Type of M
LINEAR
Egs of this
• Tennis drive
• Vertical jump
• Shot put
F passes outside the
C of M
Movement in circle (part) around axis of rotation
ECCENTRIC ANGULAR
• Tennis topspin or slice
• Curve ball / spin
• Beckham free kick
• Golf wedge shot





Throw a tennis ball into the air making it spin.
Draw a diagram that shows the centre of mass, the point of application of Force
Action/Reaction
Direction of force.
What is the scientific name given to the force resulting in the angular motion.


Using the bat and ball in your groups can you cause the ball to move in a linear motion by applying a direct force?

Can you apply an eccentric force to cause the body to move with an angular motion.

What would be a really good sporting example?



Draw a free flow diagram of a sprinter in the blocks.
Explain the Laws of motion, mass, and force.