edu2mp movement perspectives linear motion movement in a straight line of a body or body part....
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EDU2MP Movement Perspectives
Linear Motion
• Movement in a straight line of a body or body part. (Translatory motion)
• The sprinter runs from A to B.
EDU2MP Movement Perspectives
Curvilinear Motion
• Movement along a curved line.
• Most jumps are along a curved line.
EDU2MP Movement Perspectives
Linear Motion I – Middle SecondaryIntroduction to Linear Motion
speeddistance / displacement
velocityacceleration
Graphical representationdistance - time graphsspeed - time graphs
velocity - graphsLinear Motion II – Senior Secondary
Non-uniform motiondisplacement
velocityacceleration
instantaneous speedaverage speed
Uniform motionequations for uniform motion
EDU2MP Movement Perspectives
Many sports involve the throwing of a ball or other object. This article discusses the
basics of projectile motion, and for ease of understanding, we will consider that there is no air resistance. The influence of air
resistance, friction, spin, and air flow around the object is discussed elsewhere Any projectile thrown, such as a ball, can
be considered to have a vertical and horizontal velocity component, as shown in
this diagram (blue=horizontal velocity component, red=vertical velocity
component). Throughout the path of the projectile,
change occurs only in the vertical direction due to the influence of gravity, while the horizontal component of the velocity will not change. (This is not quite true, there
will be a very small slowdown in the horizontal direction due to air resistance).
EDU2MP Movement Perspectives
There are many examples of projectile motion is sport.
•Golf ball
•Basketballs
•Javelin
•Ski jumping
•Diving
•Trampoline
•Archery
•Soccer
•Football
•Cricket
EDU2MP Movement Perspectives
The following factors influence the projectiles trajectory
Angle of release
Speed of release
Height of release
Gravity
Spin
Air resistance
See java demo
EDU2MP Movement Perspectives
Spin Magnus Effect
When sports players produce curve balls, be it through throwing, kicking or hitting a ball, they are exploiting the Magnus effect.
EDU2MP Movement Perspectives
The Magnus effect causes a spinning ball moving through air (or any other fluid such as water) to produce a force perpendicular to both its spin axis and its direction of travel. This force causes the ball to curve either left or right if the spin axis is vertical. If the spin axis is both horizontal and perpendicular to its direction of travel then the ball will either descend faster or slower than it would otherwise under the influence of gravity alone.
Magnus Effect is a lifting force produced when a rotating cylinder produces a pressure differential. This is the same effect that makes a baseball curve or a golf ball slice.
The difference in surface velocity accounts for a differ-ence in pressure, with the pressure being lower on the top than the bottom. This low pressure area produces an upward force known as the “Magnus Effect.” This mechanically induced circulation illustrates the rela-tionship between circulation and lift.
EDU2MP Movement Perspectives
Friction
FrictionFriction can be defined as the resistance to motion of two moving
objects or surfaces that touch.
EDU2MP Movement Perspectives
COR
To find the coefficient of restitution in the case of a falling object bouncing off the floor, or off a racquet on the floor, use the following formula:
c = coefficient of restitution (dimensionless)h = bounce heightH = drop height
The coefficient of restitution (denoted by the symbol c in our formulas) is a measure of the elasticity of the collision between ball and racquet.
EDU2MP Movement Perspectives
And the coefficient of restitution merely tells you how much of the original kinetic energy remains after a collision of the clubhead with the golf ball.
The higher the coefficient of restitution, the faster the ball will be propelled by the clubhead for a given impact speed.
So why all the fuss over this figure?
It's because the USGA is trying its best to limit the influence of technology in golf. Theory being that golf should challenge the skill and savvy of the individual rather than the technology in his or her bag. And this is probably a good thing for the sport. After all, it would be very effective to go bass fishing by dropping depth charges over the side of your boat. Just scoop 'em up when they float to the surface. But would that really be bass fishing?
So the USGA has adopted limits of 0.830 on the coefficient of restitution a given clubface may have as part of its effort to define the boundaries of technology in the game.
EDU2MP Movement Perspectives
Factors Affecting Pathways
The pathway of an object is determined by:
• The angle of release.
• Drag force is a resistant force
• Lift force
• Type of spin
EDU2MP Movement Perspectives
• When an athlete launches himself or an object into flight gravity will act as a force pulling the athlete or object towards the ground. The flight path of the centre of gravity of a body is a curve called a parabola. The parabolic flight path depends on three factors:
• ● Speed of take off or release • ● Angle of take off or release • ● Height of the athlete's CG at take off, or CG of implement at
release• Of these, the speed of an athlete at take off, or of an implement at
release, is the most important factor. Greater speed means greater distance achieved. Air resistance can also affect the distance travelled by an athlete or implement.
•
EDU2MP Movement Perspectives
Drag Force
• Drag force is a resistance force - a force that slows the motion of a body through a fluid (air or water).
• Sportsmen reduce drag by using specialised techniques, equipment or clothing.
• Streamlining reduces form drag.
"Photos courtesy of and copyright Free Range Stock, www.freerangestock.com"
EDU2MP Movement Perspectives
Lift Force
• Lift force is a force generated perpendicular to fluid flow.
Direction of fluid
flow
Lift force
EDU2MP Movement Perspectives
Types of Spin
• Spin is the rotation of a body or object.• Torque is the force which creates spin.• The type and amount of spin depends on how
much torque is applied and where it is applied.
TOPSPIN
BACKSPIN
SIDESPIN
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