Motion and Movement
In this section we will look at how the application of the laws of motion, force,
Newtons Laws of Motion and centre of mass can help to produce improved
performance. Knowledge of these laws will help in the analysis of movement.
Motion
Motion means movement and can be divided into three main catagories.
 Linear motion
 Angular motion
 General motion (combination of linear and angular motion)
Linear motion
When a body moves in a straight or curved line, with all its parts moving
the same distance, in the same direction and at the same speed.
A good example is a tobogganist. All parts of the body and the toboggan are
moving in a straight line, the same distance, the same direction and at the
same speed.
Can you think of similar examples?
Linear motion in a curved line is very rare in human motion but can be seen in
the latter stages of shot putt. All parts of the shot are moving in a curved line,
the same distance, in the same direction and at the same speed.
Can you think of similar examples?
Angular motion
When a body, or part of a body, moves in a circle or part of a circle
about a particular point called the axis of rotation.
To produce angular motion, the movement must occur around a fixed point or
axis.
Two good example are a bicycle wheel turning about its axis, or a door
opening on its hinges.
When we apply this to human movement we think of athletes spinning,
circling, turning and somersaulting – this implies that the athlete, or part of the
athlete, is moving through a circle or part of a circle about a particular point.
More simple movements are also angular motion – when the limbs of our own
bodies move around our joints, which are fixed points. E.g. flexion and
extension of the elbow joint – the lower part is moving through part of a circle
about a particular point. Other simple movements are:
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Tapping your foot up and down to music.
Raising the arm up – to answer a question - and down again.
Completing sit-ups.
Kicking a ball over a big distance.
Swimming front crawl.
Gymnast swinging around the high bar.
General Motion
A combination of linear and angular movement.
Most movements in sport are a combination of both linear and angular motion
and so this third type of motion is the easiest to find examples for.
 During the approach to javelin – the torso of the athlete shows linear
motion by moving in a straight line with all parts moving the same
distance, in the same direction and at the same speed. The arms and
legs, however, are showing angular motion as they go through the
preparation, action and recovery of the javelin technique.
 A wheelchair athlete – the body of the athlete in the chair is displaying
linear motion, but the swinging action of the arms and the turning of the
chair’s wheels show angular motion.
Force
A push or pull that alters, or tends to alter, the state of motion of a body.
A force can perform the following functions:
1. Cause a body at rest to move.
2. Cause a moving body to:
 Change direction
 Accelerate
 Decelerate
3. Change an objects shape.
The extent to which a force has an effect depends on where the force is
applied, the size of the force, and the direction in which it is applied.
Find out what you can about Newton’s First, Second and Third Laws of
Motion. Can you find a sporting example for each?