Movements 1. Forces

Question 1

Forces

Answer 1

Muscle contraction

Question 2

Fulcrum/axis

Answer 2

Joint

Question 3

Levers

Answer 3

Limbs

Question 4

Centre of gravity

Answer 4

sacrum
Where gravity acts
Mass of all body segments evenly distributed

Question 5

Concentric

Answer 5

Muscle shortens and bulges is and isometric contraction

Question 6

Eccenteic

Answer 6

Muscle lengthens and returns to original length isotonic

Question 7

Isometric

Answer 7

Muscle under tension but not changing length

Question 8

Force

Answer 8

And influence that changes the state of rest or motion of the body

push – compression or pull – tension

External forces:
•Gravity
•water – resistance/bouancy
• Manual/mechanical forces used by therapists – passive movements and stretches mobilisation

Question 9

Law of inertia

Answer 9

Body will remain at rest or in a state of uniform motion unless acted upon by an external force

Weak quads reduce inertia

Question 10

Law of acceleration

Answer 10

The acceleration of the body is parallel directly proportional to the force acting on the body Is in the same direction of the force and inversely proportional to the mass of the body

Make exercise faster

Question 11

Law of action/reaction

Answer 11

To every action there is an equal and opposite reaction

Resistance is equal

Question 12

Magnitude

Answer 12

Size or strength of force measured in kg lbs and Newton’s

Question 13

Action line

Answer 13

Straight line through the point of application

Question 14

Resultant force

Answer 14

Combination of forces

The final effect of all these forces is the resultant force.

Resultant force = is the simplest force necessary to produce the same effect as all the forces acting together

Question 15

Linear force systems

Answer 15

To forces act along the same action line

direction of force may be an opposite direction – tension affect (Collinear force system) tug of war

Direction of force may be in same line of direction – compression affect two people moving a box

Question 16

Parallel force system

Answer 16

Direction of forces are parallel either in the same or opposite directions

Forces are coplanar but do not share the same action line- see saw

Parallel forces in opposite directions can produce a rotatory effect – force couple

Question 17

Force couple

Answer 17

Two parallel forces that are equal in magnitude Do not share the same line of action therefore produced a rotatory effect

Question 18

Force couple – pelvic control

Answer 18

Forces are equal in magnitude but opposite in direction

Muscles located at different points relative to the axis act together to produce rotation

Question 19

Concurrent force system

Answer 19

All forces act at the same point somewhere

Resultant force but on a specific line or body part rather than the whole body

Examples:

Sternal and clavicular head of pectoralis major

Question 20

Stability

Answer 20

Stability of an object refers to the ease with which it can be displaced

Question 21

Equilibrium

Answer 21

Equilibrium results when the forces acting on the body are perfectly balanced and the body remains at rest. Different types of equilibrium states reflect the level of stability.

Question 22

Stable Equilibrium

Answer 22

occurs if the forces acting on a body tend to restore it to its original position following application of a displacing force. The line of gravity always remains within the base of support, even following displacement.

A low centre of gravity, and an extensive base of support with the line of gravity falling close to the centre of the base, improves the stability

Question 23

Unstable Equilibrium

Answer 23

Little force is required to make the body topple and assume a new position. A high COG, a small BOS with the LOG falling close to the edge of the base, will mean that the LOG is easily displaced outside of the BOS

Question 24

Neutral Equilibrium

Answer 24

occurs when following the application of a displacing force, the relationship of the centre of gravity, line of gravity and base of support all remain as before eg rolling ball, sliding across a plinth.

Question 25

Line of gravity

Answer 25

The projection of the CoG on the ground, represented by a perpendicular line on the ground through CoG

Question 26

Base of support

Answer 26

All forces act here all points of contact