Biomechanics Flashcards

1
Q

Newton’s 1st law of motion

A

a body continues in its state of rest of motion unless acted upon by a force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Newton’s 2nd law of motion

A

Rate of change of acceleration to a body is proportional to the force applied to it and inversely proportional to the mass of the object.
F=ma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Momentum

A

measure of the amount of motion possessed by a moving body and can be expressed mathematically as p=mv (mass x velocity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Conservation of linear motion (COI)

A

Principle states the total momentum of the two objects before and after impact.
Perfectly elastic - the momentum of one object is transferred on contact to the other object, no loss of momentum.
perfectly inelastic - all moment lost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Impulse

A

the application of force over a period of time to change the momentum of an object
Impulse = force x time
it is a change in momentum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Newton’s 3rd law of motion

A

for every action, there is an equal and opposite reaction.
When two objects exert a force upon each other, the forces are opposite in direction and equal in magnitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

concept of conservation of momentum

A

Explains that when collisions occur, an equal and opposite force occurs resulting in a transfer of momentum from one object to the other.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

coefficient of restitution (COR)

A

Measures the elasticity of the collision between an object and a given surface.
measures how much energy remains in the object after a collision takes place.
Measured on scale of 1-0 (1-perfectly elastic, 0-perfectly inelastic)
formula - COR=square root(height bounced/height dropped)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Factors affecting COR

A

Temp of ball, increase temp - increase COR
Velocity of collision, increased V - decrease COR
equipment and material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Elasticity

A

measure of how much rebound exists after collision

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Concentric force

A

force applied to produce linear motion
(eg. Slapshot) - puck moves straight, hit in the middle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Eccentric force

A

off centre force applied to produce angular motion
(Spin on ball)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Force couples

A

when two equal, but oppositely directed forces act on opposite side of an axis of rotation.
This causes the forces that produce linear motion to cancel each other out, causing the object to rotate in a fixed position

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

angular momentum

A

Quantity of angular motion possessed by a rotating body and is expressed mathematically as:
angular momentum = angular velocity x moment of inertia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Moment of inertia (MOI)

A

refers to resistance of a rotating object to change its state of motion.
If mass of object is distributed close to the axis of rotation, the MOI is small and it is easier to rotate object. As mass of an object moves further away from the axis of rotation, the MOI increases and rotation becomes harder.
MOI=mass of object x radius of rotation
Distance of axis of rotation = radius of rotation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

conservation of angular motion

A

Means that a spinning body will continue spinning indefinitely unless an external acts on it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

MOI and angular motion

A

Increased MOI = decreased AV
increased AV = decreased MOI

18
Q

Angular momentum

A

=angular velocity + moment of inertia

19
Q

Torque

A

the turning effect created as a result of an eccentric force being applied around a pivot or axis
torque=force x distance (perpendicular distance)
Moment arm is the distance between where the force is being applied and where the torque is produced

20
Q

lever

A

To increase or magnify the force applied

21
Q

factors affecting levers

A

Length of the lever - velocity is greatest at distal end of a lever, longer lever = greater velocity at impact
the inertia of the lever - longer the lever, harder it is to rotate, increasing rotational inertia
The amount of force - the amount of force an athlete is able to generate via their muscles determines the length of the lever the athlete should use.

22
Q

Lift force

A

refers to the component of force that acts perpendicular to the direction of flow, acts at a right angle to the direction of motion.
Can act in upwards to downwards force.
only acts in objects that are spinning or not perfectly symmetrical.
Lift is created by different pressures on opposite sides of an object due to fluid flow past the objects.

23
Q

Bernoulli’s principle

A

Bernoulli’s principle states that the velocity of a fluid over a moving object determines the pressure system.
Fluid with fast velocity creates an area of low pressure while fluid flow with a slow velocity creates an area of high pressure.

24
Q

Magnus effect

A

Term used to describe the effect of rotation on an object’s path as it moves through a fluid.
it applies Bernoulli’s principle to explain the effect spin has on the trajectory or flight path of an object.

25
Q

Spin

A

when a ball is struck with an eccentric force, there is both linear and angular motion.
Rotating ball interacts with the oncoming air.
the resulting movement - curve

26
Q

Fluid flow

A

the natural of fluids in motion

27
Q

fluid resistance

A

As an object moves through a fluid, it disturbs it.
The greater the disturbance to the fluid, the greater the transfer of energy from object to fluid.

28
Q

2 factors affecting fluid resistance

A

Density (air) - the more denser the fluid, the more disturbed the fluid becomes and hence the greater the resistance
Viscosity (fluid) - the more viscous the fluid, the more disturbed the fluid becomes and hence the greater the resistance

29
Q

Types of drag

A

surface drag
Form drag
wave drag

30
Q

Surface drag

A

friction produced between fluid and surface of a moving object.
Factors affecting: velocity (H V, H SD), roughness of surface (H R, H SD), Viscosity (H Vi, H SD), Surface area (H SA, H SD)

31
Q

form drag

A

Resistance created by pressure differential between front and back of an object moving through a fluid
factors affecting: cross sectional area (H CSA, H FD), Velocity (H V, H FD), surface roughness (H SR, L FD), Shape (round vs oval)
Surface roughness decreases form drag because causes the air to cling to surface of object for longer period, causing a later separation point and hence less drag.

32
Q

wave drag

A

Resistance formed by creation of waves at the point where air and water interact.
seen as the major form of drag for swimmers
Factors affecting: velocity of wave (H V, H WD), technique (Streamline), conditions (open vs closed waters)

33
Q

boundary layer separation

A

Where boundary layer breaks away from ball.
the earlier the boundary layer separation, the greater the pressure gradient between the front and back of the ball.
Leads to increased drag.

34
Q

laminar flow

A

A type of fluid flow in which fluid moves smoothly in individual layers or streams.
fluid flow which occurs in “sheets” parallel to each other.
If there is a surface nearby, the flow lines typically run parallel to it.

35
Q

turbulent flow

A

Flow in which the velocity at any point varies erratically.
Doesn’t flow in parallel sheets, rather independent and random.

36
Q

factors affecting boundary layer separation

A

Velocity - low, boundary layer clings to surface and separation well towards rear. High, separation occurs further forward
surface roughness - rough, creates turbulent boundary layer, reducing effect of drag

37
Q

Sequential movement

A

Use larger slower moving body parts first, then smaller faster moving body segments.
initiates by getting balanced, wt widen base of support to gain a stable base of support, this allows for optimal transfer of momentum between body parts.
Each segment begins once the previous segment has reached peak velocity.
follow through in his swing to prevent deceleration of the racquet.
All forces are directed towards the target.

38
Q

balance

A

Ability to remain stable or steady or upright.
gaineds by achieving an even equilibrium/distribution of forces (weight) around the base of support.
Ensure you have a large stable base to ensue all segments rotate around a stable base.
line of gravity remains above base support
Maximise points of contact wt the ground
lower centre of gravity

39
Q

Range of motion

A

refers to the extent of a motion around a joint

40
Q

Optimal projection

A

when angle, velocity and height or release combine to meet the demands of the task.