Biomechanics Part 1

Question 1

Bernoulli’s Principle

Answer 1

An increase in velocity in fluid moving over an object creates a decrease in pressure. A decrease in velocity of a fluid moving over an object creates a increase in pressure.

Question 2

Bernoulli’s Application

Answer 2

• Label high/low pressure, high/low velocity, lift force, air resistance
• Define Bernoulli’s
• (object) tilted upward creates pressure difference
• high pressure moves to low pressure causing lift force

Question 3

Laminar Flow

Answer 3

Smooth parallel layers of air (fluid) that move around an object while in motion

Question 4

Turbulent Flow

Answer 4

Mixing of adjacent fluid at the rear of an object

Question 5

Pressure Drag

Answer 5

The pressure differential at the front and back of a object moving through a fluid. Low pressure at the back, high pressure at the front.
(Use pointed shaped objects, reducing cross sectional frontal area)
Example: tear dropped cycle helmet or surfboard

Question 6

Surface Drag

Answer 6

Drag on a object moving through a fluid and the resulting friction on the surface of the object and the fluid. Object surface smooth to reduce the surface drag.
Example: swimming caps or swim suits
(Promoting: boots with spikes or studs or underside of surfboard is smooth)

Question 7

Wave Drag

Answer 7

The interaction between the object with water and air moving through a fluid and the result of waves.
(Minimising: object is buoyant e.g surfboard or lane ropes in pool)

Question 8

Explaining Magnus Effect

Answer 8

1. Player creates spin by applying a eccentric force to a certain area (above centre, below centre or left and right of centre of ball)
2. (Apply to scenario) that side of the ball will have a boundary layer of air moving in the same direction of passing air resistance creating high velocity/low pressure.
3. On opposing side the boundary layer will collide with oncoming air resistance creating a low velocity/high pressure zone
4. The pressure differential will cause the ball to move from high pressure to low pressure, creating the Magnus effect

Question 9

Back Spin

Answer 9

Ball hit will travel higher and go further

Question 10

Top Spin

Answer 10

Ball hit will dip suddenly and not travel as far

Question 11

Levers

Answer 11

1st Class Lever (A)
2nd Class Lever (R)
3rd Class Lever (F)

Netball/Basketball Shots= 1st Class

Question 12

Force Arm

Answer 12

Distance between force and axis point

Bigger force arm greater torque produced

Question 13

Resistance Arm

Answer 13

Distance between resistance and axis point

Greater the resistance arm the greater the speed

Question 14

Torque

Answer 14

Force x Perpendicular distance of force arm

Question 15

Increasing Torque

Answer 15

Increase force applied to lever system
Increase strength 
Increase amount of motor units used in motor pathway 
Creating a longer force arm 
Decrease moment arm

Question 16

Moment of Inertia

Answer 16

Mass x radius2
The reluctancy of an object to rotate
(Smaller moment/resistant arm will aquate to a smaller moment of inertia)
(Longer moment/resistant arm will aquate to a higher moment of inertia)
Is affected by mass

Question 17

Angular Momentum

Answer 17

Moment of inertia x angular velocity

Graph order:
Angular Momentum
Angular Velocity
Moment of Inertia