REVISION

Question 1

class I lever and example

Answer 1

fulcrum between load force and applied load
atlanto-occipital joint = fulcrum
load = weight of skull
applied load = trapezius and splenius capitis

Question 2

Class II lever and give an example

Answer 2

load is between applied load/effort and fulcrum

e.g metatarsophalangeal joint = fulcrum and calf muscle = applied load and body weight = force load

Question 3

Class III lever and give an example

Answer 3

applied load is between force load and fulcrum

e.g. humeroulnar joint = fulcrum, bicep = applied load weight of forearm and wrist = load

Question 4

what is mechanical advantage and why is Class II lever mechanically advantaged and Class III lever is mechanically disadvantaged

Answer 4

effort/force load 
mechanically advantaged > 1
mechanically disadvantaged < 1
torque = weight by distance 
greater distance between fulcrum and applied load in class II in comparison to distance between force load and fulcrum means effort can create greater torque.

Question 5

newtons 2nd law

Answer 5

acceleration of object is directly proportional to net external force and inversely proportional to its mass
i.e the greater external net force = greater acceleration of object and greater the mass = slower acceleration

Question 6

newtons 2nd law formula

Answer 6

F =ma
F = force
M = mass
a = acceleration

Question 7

weight formula

Answer 7

weight x acceleration

Question 8

newtons 3rd law

Answer 8

object exert force on another object and other object exerts force of same magnitude in opposite direction

Question 9

RTA is an example of which newtons law

Answer 9

newtons 3rd law

Question 10

force formula on Newtons 2nd law

Answer 10

F = ma 
acceleration = (v2 - v1)/t 
F =m(v2 - v1)/t
Ft = m(v2 - v1)
F = force
t = time
m = mass
v1 = initial speed
v2 = final speed
increase interaction time = decreased force

Question 11

precautions for RTA

Answer 11

seatbelts
airbags
crumple zone

Question 12

how do seatbelts minimise impact force

Answer 12

prevents person from being propelled forward by inertia and hit the windscreen

Question 13

how do airbags minimise impact force

Answer 13

driver comes to rest slower
air slowly pushes out of bag
more interaction time against bag less impact force

Question 14

how do crumple zone reduce injury

Answer 14

as the car distorts it increases interaction time

reduces impact force

Question 15

energy definition

Answer 15

ability to do work

Question 16

work definition

Answer 16

force x distance

Question 17

work energy principle

Answer 17

total mechanical energy = kinetic energy + potential energy

total mechanical energy @ start = total mechanical energy +/- work done

Question 18

power

Answer 18

work done/time

rate of energy expenditure

Question 19

efficiency

Answer 19

work done/ energy expenditure

Question 20

stress

Answer 20

sectional area subjected to a force

Force / Area

Question 21

types of stress

Answer 21

compression
tension
torsion
shear

Question 22

strain

Answer 22

stress results in change in length

change in length / length

Question 23

strain example

Answer 23

tension

compression

Question 24

youngs modulus

Answer 24

stress / strain

Question 25

describe graph of stress y axis and strain x axis

Answer 25

A to B - return to original length = elastic deformation B to D - plastic deformation permanent change in length beyond B = beyond elastic limit point C = permanently deformed, maximal permissable stress point D - fracture

Question 26

describe the biomechanical forces in the bone that resist bending

Answer 26

top surface of the bone in tension tries to 'pull' surface back to original shape bottom surface 'push' molecules back to original shape under compression hollow bone = more resistance in bending

Question 27

precautions to prevent low back pain

Answer 27

maintain good posture and natural curvature of spine - to prevent crushed vertebrae feet apart = increased bos Knees bent

Question 28

centre of gravity definition

Answer 28

single point that moves in accordance with newtons simple laws of motion

Question 29

how does cog influence amputees balanced

Answer 29

COG is between 2 legs has torques of equal magnitude in opposite direction and cancel each other out COG is shifted and torque is unbalanced patient is unstable and wobbles

Question 30

unit for charge

Answer 30

coloumb

Question 31

unit for current

Answer 31

amperes

Question 32

unit for voltage

Answer 32

volt

Question 33

unit for resistance

Answer 33

ohms

Question 34

coloumb force =

Answer 34

force = constant(Q1.Q2)/r2

Question 35

static electricity

Answer 35

build up of charge that attract and repel excess charge

Question 36

safety hazard of static electricity

Answer 36

sparking - presence of flammable liquids | lack of humidity

Question 37

precautions for build up of static electricity

Answer 37

humidifiers - moisture in the air drain excess charge by attracting water molecules anti static flooring and rubber for masks surgical gowns treated with silicone all electrotherapy or ICU equipment should be earthed

Question 38

Ohm's law and how it influences physiological response to electric current

Answer 38

V = IR V = voltage I = current R = resistance resistance is inversely proportional to current wet skin - less resistance - more current

Question 39

components in a delivery system

Answer 39

``` diathermy unit active cable active electrode dispersive plate dispersive cable ```

Question 40

purpose of dispersive plate

Answer 40

to disperse RF current and prevent thermal injury

Question 41

microshock sensitive patients why that is dangerous

Answer 41

pacemakers catheters internally placed conductor internal electrical path directly to heart

Question 42

precautions for microshock sensitive patients

Answer 42

patient should not be grounded - path directly through patient and into heart that can lead to fibrillation and as it disperses infintely throughout the ground all equipment connected or near the patient should be earthed - provides path for electric current to go down to earth without going through patient

Question 43

Joule's law

Answer 43

``` E = I^2Rt E = energy I = current R =resistance t = time currently passed directly thru = tissue heating up ```

Question 44

components of circuit in short wave therapy

Answer 44

main power supply - high frequency generator and amplifier oscillator coil resonator coil variable capacitor

Question 45

Physiological effects of SWT are those of heat in general

Answer 45

``` Tissue Temperature Increase Increased Blood Flow (Vasodilation) Increased Venous and Lymphatic Flow Increased Metabolism Changes In Physical Properties of Tissues Muscle Relaxation Analgesia ```

Question 46

how ions respond to SWT

Answer 46

High frequency current - > ions accelerated along the lines of electric field. - the ions to oscillate (or vibrate) about a mean position by oscillating electric field - The ions kinetic energy is converted to heat.

Question 47

How dipolar molecules respond to SWT

Answer 47

High frequency current -> rotation of the Dipolar (sometimes referred to as simply polar) molecules. - the molecules will rotate at the same frequency as the e-m radiation Moderately efficient heating occurs because of the frictional drag between the molecules.

Question 48

how non polar molecules respond to SWT

Answer 48

The paths of the orbiting electrons become distorted, first in one direction, then in the other as the electric field oscillates.

Question 49

Capacitive method of SWT

Answer 49

Where the patient (tissue) is placed between the two electrodes, essentially acting like a capacitor

Question 50

Inductive method of SWT

Answer 50

The variable capacitor in the ‘patient circuit’ is connected in parallel with another inductance coil mounted in a single pad or electrode

Question 51

The rise in tissue temperature associated with the application of SWT depends on a factor known as

Answer 51

the Specific Absorption Rate Watts/kg