LEWIS: Mechanics Of Movement Flashcards
Linear motion is
A motion in a straight or curved line with all body parts moving the same distance at the same speed in the same direction
Linear motion is measured in 10 ways
Mass
Weight
Distance
Deceleration
Speed
Velocity
Inertia
Momentum
Scalar quantities are described in terms of
Magnitude
Scalar measurements:
Mass
Distance
Speed
Inertia
Vector quantities are described in terms of
size and direction
Vector measurements are
Weight Acceleration Deceleration Displacement Velocity Momentum
Mass is
Body tissue
Scalar
Weight is the
Force on a given mass due to gravity
Vector
Distance and displacement are used to describe a
Body’s motion
Inertia is the resistance
An object has to a change in its state of motion
Scalar
Newton’s 1st law
Bigger the mass the larger the inertia needed
Distance is the length of the path a body follows when
Moving to a point
E.g. 400m rubber
Displacement is the length of a straight line joining the
Start and finish points
E.g. 200m race on the track
Speed is the rate of change of
Position
Scalar
Equation for speed =
Distance(m)/time(s)
Equation for velocity =
Displacement(m)/time(s)
Velocity is the rate of change of position with reference to
Direction
Vector
Acceleration and deceleration are the rate of change in
Velocity
Acceleration =
Velocity increases
Deceleration =
Velocity decreases
Acceleration and deceleration =
vector
Acceleration =
change in velocity (ms-1) / time (s)
Change in velocity =
final velocity - initial velocity
Momentum is the product of
mass and velocity of an object
Momentum (kg/m/s-1) is calculated using:
mass (kg) x velocity (m/s-1)
Momentum =
vector as it has magnitude and direction
Momentum is a closed system, which means total momentum is conserved. So when 2 objects collide the total momentum stays…
the same
forces can be either :
internal or external
internal forces are generated through the contraction of
skeletal muscles
external forces come from outside the body, e.g.
air resistance and friction
2 factors affect a generated force:
size (dependent on the size and number of muscle fibres used)
direction (force applied through the middle = move in same direction as force)
Applying a force straight through the centre =
linear motion
Applying a force off-centre results in spin =
angular momentum
force =
mass x acceleration
vertical forces:
weight
reaction
horizontal forces:
friction
air resistance
(VF) weight is a
gravitational force that the Earth exerts on a body pulling it downwards
(VF) reaction occurs whenever
2 bodies are in contact with one another (Newton’s 3rd law)
(HF) Friction occurs whenever there are 2 bodies in contact with each other that try to move over one another. It acts in opposition to motion and resists the sliding/slipping motion of
2 surfaces
(HF) Air resistance opposes the motion of a body travelling through the
air
Air resistance depends on the:
- velocity of the moving body (greater velocity = greater resistance)
- cross-sectional area of the moving body (larger cross-section=greater air resistance)
- shape and surface characteristics of the moving body (streamlined = less resistance)