Kinetics Lab 8 Review 2010

8/8/2019 Kinetics Lab 8 Review 2010

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Kinetics Lab Review



Centre of Gravity/ Centre of Mass The CofG of a body is sometimes described

as its balance point, or the point about which a

body would balance without a tendency torotate

CoG depends on the arrangement of body

segments The centre of mass is an interchangeable term

for CofG



Centre of Mass

We can calculate the CoM of the body if we

know:

i) the location of the CoM of each of thesegments

ii) the location of all of the segments

We are stable when

our CoM falls within

our Base of support



Com vs. CoP



Sensory contributions to balance When we stand someone on Foam we take

away their ability to use somatosensory input

(information from skin, muscles joints).Therefore they rely more on vision and

vestibular input.

When we remove vision what are we testing?



APA-Anticipatory Postural Adjustment

• During quiet stance CoM falls

between two feet (BoS)

•In stepping the Bos is reduced to

one foot

• Lifting one leg will cause a M-L

instability if the CoM is not shifted

to a location within the remaining BoS (stance foot)

BoS

CoM



•This is accomplished by a push with the swing limb• Measured as a shift in the CoP towards the swinglimb prior to the step. This is the APA.



Forces – counter movement jump

Time

Jump take-off

Landing

F=ma



Lab Reports Add references!!!

Make sure to add Text in the Results. Don’t

need a lot of description, just tell us what youfound. Eg. “The EMG and force relationship

was non linear. As EMG increased, the force

did not increase proportionally (figure 1)”



Part A Only coordinates for forearm, therefore don’t

need to include the hand. If you have that is

fine. Don’t need to include this in your methods

Include calculations as an “appendix” at the end

of the lab.

Answer the questions for Part A in the appendix



Part B

Include parts B, C and D in your methods

section.

Include the table in part B Results section. Answer the questions in the Discussion.



Part D

APA: Graph the M-L CoP vs. A-P CoP for

the step. In your figure you can include where

the feet are (either based on your numbersfrom lab, or best estimate). Indicate which

foot is stepping.

Answer questions in Part D in Discussion



Part D

Jump:

Include Fz graphs of two jumpers. Interpret

these in the results section. Ie. Who jumpedhigher. Can you tell? What information didyou use on the graph for take off and landingetc.

Include CoP (M-L vs A-P) graph of OneJumper. What does CoP do before jump? Canwe interpret what CoM does?



What variables are we interested in?

A-P, M-L peak CoP

CoP variability

Total area of CoP

Other variables:

-Sway range

-Sway variability

-Mean sway

-Radius enclosing 90% of CoP

deviations

Kinetics Lab 8 Review 2010

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