biomechanics Flashcards
1
Q
newtons 1st law
A
- “A body continues in its state of rest or state of motion unless acted upon by an external force” Also referred to as law of inertia
2
Q
newtons 2nd law
A
The acceleration of a body is proportional to the force applied to it and inversely proportional to the mass of the object” also referred to the law of acceleration
3
Q
newtons 3rd law
A
- For every action there is an equal and opposite reaction.
4
Q
internal force
A
- Structures of the body that interact to produce movement
- E.g. action of muscles and tendons that act together to produce forces that cause movement.
5
Q
external force
A
- Result from the interaction between the body and the environment. These can include contact forces and non-contact forces.
- E.g. gravity, friction, air resistance, water resistance
6
Q
linear motion
A
- Where movement is along a straight line, there is no rotation, and all body parts move in the same direction at the same speed.
- E.g. an ice skater gliding after they completed a movement or a cyclist who stops pedalling.
7
Q
rectilinear motion
A
- Movement is linear and occurs through a straight line
- E.g. a basketball chest pass or baseball pitch where the balls path is flat and in a straight line
8
Q
curvilinear motion
A
- Movement is linear but object moves through a curved trajectory
- E.g. the pathway of a ball during a shot in netball or the flight path of a long-distance ski jumper
9
Q
angular motion
A
- Where all parts of a body move through a rotational pathway, through the same angle, in the same direction and at the same time.
- E.g. when a gymnast performs a giant circle on a bar, the entire body rotates, with the axis of rotation passing through the centre of the bar
10
Q
general motion
A
- Combination of linear and angular motion
- E.g. a cyclist may move in a straight line as a result of the rotation of the legs about the hip joint
11
Q
distance
A
- Refers to how far you have travelled from your start to finish point
- Measured in terms of total distance covered
12
Q
displacement
A
- Measures the overall change in position
13
Q
speed
A
- Measure of the distance an object travels per unit of time
- Representative of how quickly you cover a given distance
- Calculated by dividing distance travelled by time taken
14
Q
velocity
A
- Speed in a given direction
- Calculated by dividing displacement by time taken
- A change in velocity could be representative of a change in speed, change in direction, or both
15
Q
acceleration
A
- Rate at which the velocity of a body changes with respect to time
- Positive acceleration: velocity is increasing
- Negative acceleration: velocity decreasing
16
Q
internal rotation
A
- Uses joints around which the rotational movement occurs
17
Q
external rotation
A
- Occurs when body parts rotate around a point that occurs outside the body
18
Q
static balance
A
- The ability to hold a stationary position
- For example, completing a handstand, pyramid in cheerleading, swimmer/runner on the blocks at the start of a race
19
Q
dynamic balance
A
- The ability to hold a moving position to execute an outcome
- For example, catching a wave while surfing, riding a skateboard, kicking a ball in soccer
20
Q
centre of gravity
A
- Gravity acts on the body in a vertically downward direction, towards the centre of the earth through a point in the body
- The theoretical point in an object, located either inside or outside of the body, where all of the body’s mass is equally distributed
- As your position changes so does your centre of gravity
21
Q
line of gravity
A
- An imaginary vertical line passing downwards throughout the centre of gravity to the ground or surface the person is on
- The closer the line of gravity is to the limits of the base support, the less the degree of stability of the object
- Movement is easier when the line of gravity falls outside the objects base of support
22
Q
base of support
A
- Area bound by the outermost regions of contact between a body and support surface
- It refers to the area beneath an object or person that includes every point of contact that the object or person makes with the supporting surface
- These points may be a chair the person is sitting on or even feet on the ground/own body
23
Q
balance and stability are affected by?
A
- Mass of the object – the greater the mass of an object the greater the stability
- Size of the base of support – the greater area of support the greater the stability
- Height of the centre of gravity above base of support – the lower the greater the stability
- Position of line of gravity relative to base of support -
- Increasing BOS in direction of oncoming force
- Positioning COG near edge of BOS in direction of oncoming force
24
Q
force
A
- The concept of force is common to all newtons laws
- Force is the pushing or pulling effect of a body on another body that can:
- Get objects moving
- Stop objects moving
- Change the direction of a moving object
- Change the speed of a moving object
- Balance another force to keep an object still
25
internal force
- Structure of the body that interact to produce movement
| - E.g. action of muscles and tendons that act together to produce forces that cause movement
26
external force
- Result from the interaction between the body and the environment. These can include contact and non-contact forces
- E.g. gravity, friction, air resistance, water resistance
27
contact forces
- the forces that act on objects that come into direct contact with one another.
- E.g. frictional forces, ground forces, air resistance, water resistance
28
non-contact forces
the forces that act on the objects without coming into direct contact with one another. E.g. gravity
29
inertia
- Describes the amount of resistance to a change in an objects state of motion
- Is directly proportional to an objects mass
- Thus the greater the mass of the object, the greater its inertia, and the greater, the force required to initiate its movement or change its state of motion
30
momentum
- A measure of the amount of motion possessed by a moving body it is the product of mass and velocity
- An object can only have momentum if it is moving
- The greater its momentum, the more force that needs to be applied to either stop or slow the object down
- As a result when two bodies collide, the one with the most momentum will be least affected
31
impulse
- The application of force over a period of time to change the momentum of an object
