lab 5: force plate

Question 1

what does force plate measure

Answer 1

measures the forces exerted by the body

Question 2

in gait/balance activities, what are force plates used to measure (2)

Answer 2

1) GRF
2) centre of pressure

Question 3

what is newtons 3rd law

Answer 3

for every force, there is a reaction force that is equal in magnitude and opposite direciton

Question 4

GRF acting in contrast to your body pushing on the floor is an example of what law of newtons

Answer 4

newton’s 3rd law

Question 5

where and during what activities does ground reaction force act

Answer 5

act on the foot during walking, jumping, running

Question 6

what are the 3 components of ground reaction force

Answer 6

has 3 components
(vertical, med/lat, ant/post)

Question 7

why does ground reaction force increase from 0-10% of stance

Answer 7

you are double support (so it will never be over 100) but it is increasing because you are adding weight (body weight shifting onto the leg)

Question 8

be able to explain the 2 peaks and 1 valley in the ground reaction force

Answer 8

.

Question 9

the first peak of vertical ground reaction force is during what part of phase

Answer 9

loading response/midstance

Question 10

the second peak of vertical ground reaction force is during what part of phase

Answer 10

preswing/pushoff

Question 11

what are the ground reaction force measures

Answer 11

peak (max ground reaction force)
loading rate = peak/time (it takes to get to peak)
pattern recognition (principal component analysis0

Question 12

what is loading rate of GRF

Answer 12

peak/time (that it takes to get to the peak)

Question 13

what is an example of pattern recognition in terms of ground reaction force measures

Answer 13

principal component anaylsis

Question 14

what is cop (centre or pressure)

Answer 14

single point which a single force is considered to act through
=point where GRF is considered to act on the foot

Question 15

where is the point where GRF is considered to act on the foot

Answer 15

the centre of pressure

Question 16

what are the 3 components pf the force plate

Answer 16

top plate
bottom plate
sensors in between the plates

Question 17

what is another name for common force plate sensors

Answer 17

transducers

Question 18

what are the 2 common sensors of force paltes

Answer 18

piezoelectric
strain gauge

Question 19

explain piezoelectric sensors

Answer 19

consists of a crystal when pressure is applies, there is a change in electrical current

Question 20

which sensor type does this apply to: consists of a crystal when pressure is applies, there is a change in electrical current

Answer 20

piezoelectric

Question 21

explain strain gauge sensors

Answer 21

metal plate/beam is deformed, changes electrical resistance

Question 22

which sensor type does this apply to: metal plate/beam is deformed, changes electrical resistance

Answer 22

strain gauge

Question 23

during force plate sensors, the changes in electricity are calibrated to what

Answer 23

the known forces at the manufacturer

Question 24

what is the wii fit

Answer 24

cheap force plate with 4 strain gauges

Question 25

what can the WII fit measure (2)

Answer 25

1) vertical GRF (not other direction) 2) COP

Question 26

force plates provide an analog or digital signal

Answer 26

analog

Question 27

true or false: force plates provide a digital signal

Answer 27

false, analog

Question 28

when is analog converted to a digital signal in force plates

Answer 28

analog is converted to digital signal prior to computer storage

Question 29

analog is a continuous waveform or discrete packets of data

Answer 29

continuous waveform

Question 30

digital is a continuous waveform or discrete packets of data

Answer 30

discrete packets of data

Question 31

does radio use analog or digital

Answer 31

analog

Question 32

be able to see the difference in graphs for analog vs digital

Question 33

continuous signal is associated with analog or digital

Answer 33

analog

Question 34

discrete packages are associated with analog or digital

Answer 34

digital

Question 35

what is the sampling frequency (rate) when converting analog to digital

Answer 35

how often you convert the analog signal the digital signal =number of samples you take per second (Hz=samples/second)

Question 36

what is the formula for sampling frequency (rate)

Answer 36

=number of samples you take per second (Hz= samples/second)

Question 37

sampling frequency should be x2 the maximum frequency within the analog system according to what theroem

Answer 37

Nyguist

Question 38

Nyquist theoem states that sampling frequency should be x2 what

Answer 38

the maximum frequency within the analog system

Question 39

Nyquist theoem states that sampling frequency should be BLANK times the maximum frequency within the analog system

Answer 39

2 times

Question 40

what is the maximum frequency of ground reaction force during walking

Answer 40

15Hz

Question 41

if the maximum frequency of ground reaction force during walking is 15 Hz (analog), what should the sampling frequency be

Answer 41

15 x 2 =30 Hz