Biomechanics

Question 1

Newtons 3 Laws

Answer 1

The law of inertia:a body at rest will remain at rest, and a moving body will continue to move at a constant speed in the same direction unless acted upon by an unbalanced force

Law of acceleration: force is directly proportional to mass and acceleration

Action-reaction:for every action there is an opposite and equal reaction

Question 2

Momentum

Answer 2

Momentum refers to that once a body is moving the momentum of the body is a product of the mass and velocity

Question 3

Impulse

Answer 3

Impulse is the change of momentum of a body over a given time

Question 4

Levers

Answer 4

1st class: effort downwards, pivot, load downwards
2nd class: pivot, load downwards, effort upwards
3rd class: pivot effort upwards, load downwards

Question 5

Torque

Answer 5

Defined as a force to cause rotation

Question 6

Balance

Answer 6

The ability to maintain the line of gravity within the base of support

Question 7

ROM

Answer 7

The flexibility of movement at a joint

Question 8

Drag

Answer 8

The force which opposes the relative motion of an object through friction

Question 9

Bernoulli’s principle

Answer 9

Increase in the speed of a liquid will decrease the pressure and a decrease in the speed of a liquid will increase the pressure

Question 10

Magnus effect

Answer 10

Defined as the force that creates lift

Question 11

Laminar flow

Turbulent flow

Answer 11

Laminar: fluid travels smoothly in regular paths
Turbulent: fluid undergoes irregular fluctuations and mixing

Question 12

Form drag

Answer 12

Form drag: created by pressure difference between front and back of a moving object through liquid
Factors affecting form drag
-cross sectional area eg cyclist in a crouched vs upright position
-Velocity of the object, higher speed greater from drag
-shape of object, round ball vs oval ball

Question 13

Surface drag

Answer 13

Friction produced between fluid and surface
Factors affecting surface drag
-velocity of object
-roughness of object, this is why athlete wear tight fitting clothes in skating, cycling etc
-surface area of object

Question 14

Wave drag

Answer 14

Resistance formed by the creation of waves
Factors affecting form drag:
-velocity of the wave
-technique, more streamlined less wave drag, underwater less wave drag etc
-open water vs closed conditions

Question 15

Coefficient of restitution

Answer 15

Measures elasticity of the collision between an object and a given surface
Factors affecting CoR
-equipment eg baseball bat can be wooden or aluminum
-condition of balls
-condition of playing surface

Question 16

Angular momentum

Answer 16

Angular velocity is the speed of a rotating object
Moment of inertia is the resistance of a rotating object to change its state of motion
Angular momentum is angular velocity x moment of inertia

Question 17

Angular momentum and Moment of inertia

Answer 17

If body’s mass is close to the axis of rotation its easier to manipulate
Moment of inertia would be smaller increasing angular velocity
Moving mass away from point of rotation decreases angular velocity

Question 18

Boundary layer

Answer 18

Thin layer of air surrounding the ball