1. PE - Biomechanics

2. Today we’ll look at… Newtons laws 1,2,3 Forces and what they can do?
Centre of mass and stability
Types of motion

3. Newton’s First Law of Motion
A body continues in a state of rest or uniform velocity unless acted upon by an external force.
Sporting Examples:
“ A football will stay on the penalty spot until kicked”
“A hockey ball will remain still until hit by the stick”
“ A football will roll until slowed by friction or another player”
“ A hockey ball will not fall from the air without the application of gravity”

4. Newton’s First Law of Motion
A body continues in a state of rest or uniform velocity unless acted upon by an external force.
No Force
No Movement =
Force
Movement

5. Newton’s First Law of Motion
A body continues in a state of rest or uniform velocity unless acted upon by an external force.
PUSH or PULLS can alter a body (object) in the following ways
Cause a body to move (as seen in the previous slide)
Cause a body to accelerate
Cause a body to decelerate
Cause a body to change direction
Cause a body to change shape

6. Forces Can - Wind Cause a body to accelerate
Sporting example: Sailing boat.
The force that causes the boat to acceleration is the wind.

7. Forces Can - Wind Cause a body to decelerate
Sporting example: Sailing boat.
The force that causes the boat to deceleration is the wind.

8. Forces Can - Cause a body to change direction Sporting example: Tennis
The force that causes the Ball to change direction is the racquet impact.

9. Ball shape is compressed by the force of the club head on impact
Forces Can -
Ball shape is compressed by the force of the club head on impact
Cause a body to change shape
Sporting example: Golf
The force that causes the ball to change shape is the impact from the club head.

10. Newton’s Second Law of Motion
When a force acts on an object, the motion experienced by the object is proportional to the size of the force and in the direction in which it is applied.
Sporting Examples:
“If you kick a football hard, it will go a long way”
“If you kick a football softly it wont go very far”
“If you hit a hockey ball to the left, it will go left”
“If you hit a hockey ball to the right, it will go right”

11. Newton’s Third Law of Motion
For every action there is an equal and opposite reaction.
Sporting Examples:
“If a rugby player pushes to the left with their foot, they swerve to the right.”
“A high jumper needs to push down on the ground to be able to go up.”
A football goalkeeper needs to push to the left with their feet in order to dive to the right.”

12. Action force is the goal keeper pushing down into the floor
Reaction force is the goal keeper lifting into the air in the opposite direction
REACTION FORCE
Action force is the goal keeper pushing down into the floor

13. Centre of Mass An imaginary point which is movable and is where the
mass of an object
is concentrated.
Centre Of
Mass

14. As the mass of the arms move up so will the centre of mass

15. Stability
Stability is dependant on the Centre of Mass being directly above the Base of Support
Centre Of
Mass
Base of
Support

16. Stability STABLE Centre Of
Mass
Stability is dependant on the Centre of Mass being directly above the Base of Support
Line of
Gravity
Base of
Support
STABLE

17. Stability
Stability is dependant on the Centre of Mass being directly above the Base of Support
Centre Of
Mass
Line of
Gravity
Base of
Support
UNSTABLE

18. Remember Centre Of Mass doesn’t always need to be inside the body

19. Stability is dependant on 4 things
Position of the centre of mass?
Size of the base
of support?
Mass of the
Athlete?
Where the line of gravity is?

20. Motion - Linear
When a body moves in a straight line with all its parts moving the same DISTANCE, DIRECTION, and SPEED
Everything is moving in the same direction at the same speed
SPORTING EXAMPLE = THE BOB SLEIGH (TOBOGGAN)

21. SPORTING EXAMPLE = BENDING YOUR ARM IN A TENNIS SERVE
Motion - Angular
When a body or part of a body moves in a circle or part of a circle about a point (the axis of rotation).
Circular motion about a point. i.e. The elbow being fixed when the forearm moves in a half circle in a tennis serve
Axis of rotation
SPORTING EXAMPLE = BENDING YOUR ARM IN A TENNIS SERVE

22. General motion is a combination of Linear and Angular motion
Motion – General
General = Angular +Linear
General motion is a combination of Linear and Angular motion
Sporting examples
Javelin
Wheel chair athletics
Swimming
Running