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Sports Science > Biomechanics > Flashcards

Biomechanics Flashcards

1
Q

what is newtons first law?

A

‘A body will remain at rest or in uniform (constant) motion in a straight line unless acted upon by an external force’

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2
Q

what are examples of newtons first law in sport?

A
  • A tennis ball hit into the air will continue to travel in a straight line without gravity or air resistance (both external forces).
  • A soccer ball resting on the penalty spot will remain stationary unless kicked (external force).
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3
Q

what is newtons second law?

A

‘A force applied to an object will produce a change in motion (acceleration) in the direction of the applied force that is directly proportional the size of the force’
F = mass x acceleration

Simply put, increasing the force means increasing acceleration, while increasing the mass of an object means decreasing acceleration.

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4
Q

what are examples of newtons second law in sport?

A
  • If the same force is applied to a soccer ball and a 5kg medicine ball (from a kick), the medicine ball will accelerate less than the soccer ball as its mass is greater.
  • A cricket ball hit with greater force will move off with greater acceleration as the mass of the ball is constant.
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5
Q

what is newtons third law?

A

‘For every action there is an equal and opposite reaction’
When two objects come into contact with one another, they exert forces that are equal in size but opposite in direction to each other.

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6
Q

what is an example of newtons third law in sport?

A
  • When a tennis ball is hit, it is easy to see the force the racquet applies on the ball because the ball changes direction and accelerates. The reaction force of the ball is harder to see. This is because the racquet has a much greater mass than the ball, and the change in its acceleration is very small.
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7
Q

what is projectile motion?

A

Projectile motion looks at the factors that affect the movement path of an object or the human body whilst in the air.

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8
Q

what is a projectile?

A

A projectile is an object propelled (kicked, thrown, hit, etc) into the air or water by an external force.

A projectile can be an object such as a discus, football or arrow, or a human body performing gymnastics or diving skills.

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9
Q

what are the two forces that influence projectiles?

A

Gravity
Air Resistance

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10
Q

what are the factors affecting the path of the projectile?

A
  • Angle of release
  • Height of release
  • Speed of release
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11
Q

what is angle of release?

A

The angle, relative to the ground, at which a projectile is projected into the air.

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12
Q

what will angle of release determine?

A

The angle of release will determine:
Time in air.
Horizontal distance object moves.

The Ideal angle of release is 45 degrees from ground level. However, some sporting situations require that the angle of release to be higher or lower than 45 degrees. (Refer to the diagram on the next page)

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13
Q

what is the height of release?

A

Many sporting skills involve projecting the ball from a given height above ground level.

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14
Q

what does the height of release determine?

A

The greater the height of release of a projectile, the greater the horizontal distance it will cover, providing the same force is applied.
As the height of release increases, the optimal angle of release decreases.

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15
Q

what is the speed/velocity of release?

A

The speed of a projectile at the instant of release.

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16
Q

what does the speed/velocity of release determine?

A

The higher the speed/velocity of release, the greater the distance a projectile will carry.

The speed of release of a projectile is far more important than the angle or height of release.

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17
Q

what are the types of projectile paths?

A

High trajectory has a higher flight time. In grid iron this increases the `hang time’ of the ball and allows the team to move into position.

Parabola trajectory travels the longest distance. In shot put or discus this has the most desirable flight trajectory.

Flat trajectory has the quickest flight time. In softball, a hard, flat pitch will get to the catcher’s glove the quickest.

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18
Q

when is an object in equilibrium?

A

An object is in equilibrium when there are no unbalanced forces or torques acting upon it.

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19
Q

what are the two types of equilibirum?

A

Static and dynamic

20
Q

what is equilibrium?

A

A state in which there is a balance of forces or influences in opposition to each other.

21
Q

what is static equilibrium?

A

A state of equilibrium where a set position has to be maintained for a long period of time.
Zero velocity and zero acceleration
Refers to the body at rest or motionless.
Gymnastics - holding a pose on balance beam.
Starting block in sprints.

22
Q

what is dynamic equilibrium?

A
  • A state of equilibrium that can be easily altered.The individual’s capacity to execute an activity or sportive action while maintaining body stability.
    Constant velocity
    Refers to the body in motion with unchanged acceleration created by balanced forces
    Team sports
    200m sprint in athletics
    Wheelchair basketball
    Speed skating
23
Q

what is balance?

A

The ability of your body or an object to control equilibrium. This is skills based.
The ability to maintain the body’s center of gravity over its base of support

24
Q

what is stability?

A

The ability of a body to resist being moved or changing its equilibrium.
How difficult it is to disturb your balance.

25
Q

what are the factors that affect balance and stability?

A
  • base of support
  • centre of gravity
  • line of gravity
  • mass of the body
26
Q

what is the centre of gravity?

A
  • The central point of an object, about which all of its weight is evenly distributed and balanced.
  • The C of G will change as the position of the body changes.
  • The higher the C of G the less stable.
27
Q

what is base of support?

A
  • The base of support is the area of an object that is in contact with the surface supporting it.
  • The sections of your body in contact with the ground/surface.
  • Generally, the smaller the base of support (B of S) the less stability.
28
Q

what is the line of gravity?

A
  • An imaginary line that passes through the centre of gravity and continues down into the centre of an object’s base of support.
  • The further an object’s line of gravity from its base of support, the greater the instability and rotation.
29
Q

what is mass of the body?

A
  • Mass is the amount of matter a body has.
  • Measure mass by weight in kg.
  • The greater the mass pressing vertically downwards, the more stable the body.
30
Q

what are the factors that affect balance and stability during movement?

A
  • Walking throws body in and out of balance with each step, placing the center of gravity beyond base of support
  • A large component of sprint acceleration is created by falling forward, placing the center of gravity beyond base of support
  • Jumping attempts to raise body’s center of gravity upward
31
Q

how to increase stability and balance?

A
  • Lowering an object’s centre of gravity
  • Ensuring the line of gravity is over the base of support
  • Increasing the size of the base of support
  • Increasing the friction between two or more bodies
  • Increasing the mass of an object
  • Extending the base of support in the direction from which a force is coming.
32
Q

what is a lever?

A

A lever is a rigid structure with a pivot point or axis of rotation

33
Q

what do levers do in regard to energy?

A

Transmits and changes mechanical energy from one place to another

34
Q

how are levers classified?

A

Levers are classified depending on the location of axis, force and resistance in relation to one another.
Levers are categorised as first class, second class, third class.

35
Q

what are levers in the human body?

A

The musculoskeletal system creates levers around every joint. These allow us to move.
- the joints act as the axis
- the muscles act as the force
- the resistance is any body part or object that needs to be moved.

The body contains all types of levers, however 3rd class levers are the most common.

36
Q

what are the parts of a lever?

A

Axis: The point about which the lever rotates

The resistance: The load the lever is trying to move

The force: The action, or work done by the muscles, that causes the resistance to move

37
Q

how does ARF help to find out what type of lever something is?

A

If ‘A’ is in the middle it is 1st Class
If ‘R’ is in the middle it is 2nd Class
If ‘F’ is in the middle it is 3rd Class

38
Q

what is a first class lever?

A

The axis is between the resistance and the force
Eg. a seesaw,
There are very few in the human body.
FAR

39
Q

what is a second class lever?

A

The resistance is between the axis and the force
Allows for great force
E.g. wheelbarrow or push up, raise up on toes
FRA

40
Q

what is a third class lever?

A

The force is between the axis and the resistance.
The most common lever in the body
Lower force but great speed/velocity and range of movement
E.g. bicep curl, kicking a ball, a tennis shot

41
Q

what is mechanical advantage?

A

The mechanical advantage is the ratio of the force arm to the resistance arm.
Mechanical advantage = Force arm/ resistance arm

42
Q

what is the force arm?

A

The force arm is the distance from the axis to the force

43
Q

what is the resistance arm?

A

The resistance arm is the distance from the axis to the resistance

44
Q

what happens when there is a mechanical advantage?

A

Mechanical advantage: When the force arm is longer than the resistance arm

  • The force required to move the load is less than the resistance. That is, greater weight can be moved with less effort.
  • Smaller range of motion achieved.
  • Mechanical Advantage greater than 1
  • All second-class levers.
45
Q

what happens when there is a mechanical disadvantage?

A

Mechanical disadvantage: When the resistance arm is longer than the force arm

  • There is an increased range of motion and speed.
  • Greater force needs to be applied but it only needs to be applied over a smaller distance.
  • Mechanical advantage less than 1
  • All third-class levers.
46
Q

what will a longer lever result in?

A

A longer lever will result in greater velocity and force being produced.

47
Q

lever length though anatomical levers?

A
  • Anatomical levers in the human body are extended with racquets, bats etc.
  • This increases the distance from the axis to the resistance so the resistance arm is longer than the force arm.
  • A greater force is required to swing the racquet but the advantage is an increase in range of motion and velocity at the end of the lever.
  • More velocity at the end of the lever = greater velocity of the ball
  • Children will use equipment that is smaller as the shorter lever is easier for them to control.

Sports Science (3 decks)

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