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REVISION Flashcards

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Physics 101 flashcards AP® Physics flashcards
1
Q

class I lever and example

A

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

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2
Q

Class II lever and give an example

A

load is between applied load/effort and fulcrum

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

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3
Q

Class III lever and give an example

A

applied load is between force load and fulcrum

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

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4
Q

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

A 
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.
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5
Q

newtons 2nd law

A

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

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6
Q

newtons 2nd law formula

A

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

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7
Q

weight formula

A

weight x acceleration

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8
Q

newtons 3rd law

A

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

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9
Q

RTA is an example of which newtons law

A

newtons 3rd law

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10
Q

force formula on Newtons 2nd law

A 
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
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11
Q

precautions for RTA

A

seatbelts
airbags
crumple zone

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12
Q

how do seatbelts minimise impact force

A

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

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13
Q

how do airbags minimise impact force

A

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

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14
Q

how do crumple zone reduce injury

A

as the car distorts it increases interaction time

reduces impact force

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15
Q

energy definition

A

ability to do work

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16
Q

work definition

A

force x distance

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17
Q

work energy principle

A

total mechanical energy = kinetic energy + potential energy

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

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18
Q

power

A

work done/time

rate of energy expenditure

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19
Q

efficiency

A

work done/ energy expenditure

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20
Q

stress

A

sectional area subjected to a force

Force / Area

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21
Q

types of stress

A

compression
tension
torsion
shear

22
Q

strain

A

stress results in change in length

change in length / length

23
Q

strain example

A

tension

compression

24
Q

youngs modulus

A

stress / strain

25
Q

describe graph of stress y axis and strain x axis

A

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

26
Q

describe the biomechanical forces in the bone that resist bending

A

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

27
Q

precautions to prevent low back pain

A

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

28
Q

centre of gravity definition

A

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

29
Q

how does cog influence amputees balanced

A

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

30
Q

unit for charge

A

coloumb

31
Q

unit for current

A

amperes

32
Q

unit for voltage

A

volt

33
Q

unit for resistance

A

ohms

34
Q

coloumb force =

A

force = constant(Q1.Q2)/r2

35
Q

static electricity

A

build up of charge that attract and repel excess charge

36
Q

safety hazard of static electricity

A

sparking - presence of flammable liquids

lack of humidity

37
Q

precautions for build up of static electricity

A

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

38
Q

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

A

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

39
Q

components in a delivery system

A 
diathermy unit
active cable
active electrode
dispersive plate
dispersive cable
40
Q

purpose of dispersive plate

A

to disperse RF current and prevent thermal injury

41
Q

microshock sensitive patients why that is dangerous

A

pacemakers
catheters
internally placed conductor
internal electrical path directly to heart

42
Q

precautions for microshock sensitive patients

A

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

43
Q

Joule’s law

A 
E = I^2Rt
E = energy
I = current
R =resistance
t = time
currently passed directly thru = tissue heating up
44
Q

components of circuit in short wave therapy

A

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

45
Q

Physiological effects of SWT are those of heat in general

A 
Tissue Temperature Increase
Increased Blood Flow (Vasodilation)
Increased Venous and Lymphatic Flow
Increased Metabolism
Changes In Physical Properties of Tissues
Muscle Relaxation
Analgesia
46
Q

how ions respond to SWT

A

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.
47
Q

How dipolar molecules respond to SWT

A

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.

48
Q

how non polar molecules respond to SWT

A

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

49
Q

Capacitive method of SWT

A

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

50
Q

Inductive method of SWT

A

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

51
Q

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

A

the Specific Absorption Rate Watts/kg

Physics (9 decks)

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