biomechanics

Question 1

what is newtons second law?

Answer 1

acceleration - the acceleration of an object is directly proportional to the magnitude of force applied to it and inversely proportional and to the mass of the object. The object will accelerate in the same direction as the force applied to it.

Question 2

velocity:

Answer 2

displacement / time

Question 3

speed:

Answer 3

distance / time

Question 4

momentum:

Answer 4

mass x velocity

Question 5

conservation of momentum:

Answer 5

After a collision between two objects or more, the momentum of all the bodies will be conserved after the collision

Question 6

angular momentum:

Answer 6

Moment of inertia x angular velocity.

Question 7

moment of inertia:

Answer 7

mass x radius^2. the reluctancy of an object to rotate. smaller resistance arm means smaller MOI. larger resistance arm means larger MOI

Question 8

torque:

Answer 8

force x perpendicular distance of lever arm. eccentric or off centre force.

Question 9

how to increase torque:

Answer 9

• increase perpendicular distance of torque applied
• decrease resistance arm size
• increase force applied
• increase motor unit firing ability (via gym program)
• apply force as close to 90 degrees perpendicular as possible

Question 10

what types of levers are there:

Answer 10

• 1st class
• 2nd class
• 3rd class

Question 11

1st class lever:

Answer 11

axis in the middle

- catapult, javelin throw, basketball free throw

Question 12

2nd class lever:

Answer 12

resistance in the middle

- wheelbarrow, high jump, volleyball spike

Question 13

3rd class lever:

Answer 13

force in the middle, designed for speed

- every other human joint/movement

Question 14

force arm:

Answer 14

the distance between the force and the axis. the longer the force arm, the greater the torque that can be produced

Question 15

resistance arm:

Answer 15

the distance between the resistance and the axis. the longer the resistance arm, the greater the speed produced by the arm

Question 16

how to increase newtons second law:

Answer 16

1. hit object harder by: bigger back swing, use larger range of motion, get a run up prior to contact with ball, get stronger by gym program
2. apply larger impulse: larger follow through
3. aim in intended direction more accurately: follow through that way
4. use lighter object to modify game for beginners or younger players

Question 17

impulse:

Answer 17

force x time. the application of force over a time period.

Question 18

how to increase impulse:

Answer 18

• increase force applied: getting run up, use more motor units, bigger range of motion, greater implementation of segmental interaction
• increase the amount of time you apply force for by: following through

Question 19

coefficient of restitution:

Answer 19

• the ratio between final relative velocity of an object compared to the initial relative velocity of the object after a collision.
• the bounciness and springiness of a ball

Question 20

what does 1 mean in coefficient of restitution and what sporting ball is an example:

Answer 20

• a perfectly elastic collision

- non existing

Question 21

what does 0.01 to 0.99 mean in coefficient of restitution and what sporting ball is an example:

Answer 21

• an imperfectly elastic collision

- netball or basketball

Question 22

what does 0 mean in coefficient of restitution and what sporting ball is an example:

Answer 22

• a perfectly inelastic collision

- shot-put

Question 23

what effects the coefficient of restitution:

Answer 23

heat

Question 24

what is Bernoullis principle?

Answer 24

when an object is moving through a fluid, the velocity placed on the object is inversely proportionate to the pressure on the object.

Question 25

lift:

Answer 25

the perpendicular force of an object due to the shape/angle of the object moving through a fluid.

Question 26

what are the 2 types of fluid flow:

Answer 26

- laminar | - turbulant

Question 27

laminar flow:

Answer 27

smooth parallel layer of air (fluid) that moves around an object when moving through that fluid medium.

Question 28

turbulant flow:

Answer 28

the mixing of an adjacent fluid particles at the rear of an object moving through the fluid vortex/Eddie like characteristics of air particles. fast moving, chaotic nature

Question 29

boundary layer:

Answer 29

- the immediate layer of fluid on/near the surface of an object as it moves through that fluid - golf balls, panels on soccer ball

Question 30

smooth sphere balls:

Answer 30

- has laminar flow going over, however the fluid detaches early causing greater differential from the front and back. low pressure at the back, high pressure at the front

Question 31

dimpled/panelled balls:

Answer 31

- promote turbulent flow around the ball in a boundary layer. separates from the ball/closer to the back, causing smaller pressure.

Question 32

drag:

Answer 32

- the force enacted on an object as it moves through a fluid | - occurs when there is direct contact

Question 33

pressure/form drag:

Answer 33

- pressure differential between the front and back of an object moving through a fluid - high pressure at the front, low pressure at the back

Question 34

how to minimise pressure/form drag:

Answer 34

- taper the shape

Question 35

surface drag:

Answer 35

- the drag created on an object moving through a fluid and the resulting friction created on the surface of the object

Question 36

how to minimise surface drag:

Answer 36

- make the object as smooth as possible (swimming cap, shaved body, glossy paint on a car or boat)

Question 37

how to increase surface drag:

Answer 37

- footy boots, sprinting spikes, surfboard wax, cricket ball for swing

Question 38

wave drag:

Answer 38

- the drag created as an object/body interacts and moves through both water and air at the same time. as this occurs it causes waves to be generated which resists the object moving through the water.

Question 39

how to minimise wave drag:

Answer 39

- increase the buoyancy of the object - travel underwater completely if possible - smaller length of watercraft

Question 40

buoyancy:

Answer 40

- the ability of an object to float and/or rise to the top of a fluid