03-02: Biomechanics

Question 1

Newton’s Laws of Motion: 1st Law

Answer 1

Law of Inertia: Tendency of an object to stay at rest or in motion

Question 2

Newton’s Laws of Motion: 2nd Law

Answer 2

Law of Acceleration: Acceleration depends on strength of force (Force = Mass x Acceleration)

Question 3

Newton’s Laws of Motion: 3rd Law

Answer 3

Law of Action/Reaction: Every action has an equal opposite reaction

Question 4

Gravity

Answer 4

9.8 meters/sec (2)

Question 5

Force

Answer 5

Vector quantities; Push or pull

Question 6

Characteristics of Force

Answer 6

Magnitude, direction, point of application

Question 7

Linear Force

Answer 7

Two or more forces acting along the same line

Question 8

Parallel Forces

Answer 8

Occur in the same plane and same or opposite direction

A third force must be between the two parallel forces and must be of sufficient strength to counter the other two forces.

Question 9

Concurrent forces

Answer 9

Two or more forces must act from a common point, but pull in two different directions; shown graphically using Parallelogram method

Question 10

Resultant force

Answer 10

Net effect of concurrent forces

Question 11

Force Couple

Answer 11

Two forces act in EQUAL but OPPOSITE direction resulting in turning; Force-Counterforce

Ex: Opening a jar

Question 12

Torque

Answer 12

The ability of force to produce rotation about an axis

Question 13

Torque formula

Answer 13

• Force x Distance

- Depends on amount of force and distance of the lever from its axis

Question 14

Moment Arm

Answer 14

Perpendicular distance

Question 15

Stabilizing Force

Answer 15

Occurs when the force is too close to axis

Question 16

Angular force

Answer 16

Movement force - Greatest when angle of pull is at the 90 degree point

Question 17

Dislocating joint

Answer 17

Force is directed away from the joint - occurs past 90˚

Question 18

How does patella promote mechanical advantage?

Answer 18

Patella changes vector force of quadriceps tendon, allowing knee to flex/extend

Question 19

Stability

Answer 19

Occurs when all torques acting on an object are equal in force

Question 20

COG

Answer 20

Center of Gravity

Question 21

BOS

Answer 21

Base of Support

Question 22

LOG

Answer 22

Line of Gravity

Question 23

6 Principles of Stability

Answer 23

1. The lower the COG, the more stable the object
2. COG and LOG must remain within BOS for an object to remain stable
3. Stability increases as BOS is widened
4. The greater the mass, the greater the stability
5. Greater friction between the supporting surface and BOS result in greater stability
6. People have better balance when focusing on a stationary object

Question 24

Components of Levers

Answer 24

Resistance, Axis, Force, Resistance Arm, Force Arm

Question 25

Mechanical Advantage

Answer 25

MA = FA/RA, Ratio between the force arm and the resistance arm

Question 26

1st Class Lever

Answer 26

Axis is between force and the resistance - Best for balance (either power or speed)

Question 27

2nd Class Lever

Answer 27

Resistance in the middle with axis and force on opposite ends - Best for power - Initial Force Arm is far from axis

Question 28

3rd Class Lever

Answer 28

Force in the middle of axis and resistance - Best for ROM; Most common lever in the body, built for range

Question 29

Force Formula

Answer 29

F x Fa = R x Ra

determine force
F = R x Ra/Fa

Question 30

Fa (Force Arm)

Answer 30

• Measures from insertion to axis
• Insertion farther from axis = power
• Insertion closer to axis = speed/range