S2- Lab 2- Force and Motion Analysis

Question 1

What is the difference between an image captured at 1/50th shutter speed and 1/500th shutter speed?

Answer 1

1/50 means that the camera is open for a relatively long time- 1/50th of a second, which makes the image LIGHTER

1/500th means that the camera is open for a relatively short time- 1/500th of a second, which makes the image DARKER

Question 2

What is the difference between frame rate and shutter speed?

Answer 2

Frame rate= photos taken per second

Shutter speed= how long the shutter on the camera is open for

Question 3

What are the advantages and disadvantages of using a faster shutter speed?

Answer 3

There will be a DARKER image, but it can BE LESS BLURRY due to more shutters

1/50 th would be LIGHTER but most likely more BLURRY as it’s slower

Question 4

What is the affect of aperture on traditional cameras?

Answer 4

Apature= smaller= better - the opening though which light is let through

=focus length/ diameter of hole

Iris= light controls

Gain setting= the diameter of the image

Question 5

How do you capture force plate data?

Answer 5

Using Biowear software

Record the vertical (Fz) and horizontal (Fy) ground reaction forces normal walking

Calculate the weight of each participant
(mass x 9.81)

Record the ‘peak force’ and the time of the foot-ground contact in seconds

Question 6

Why is it useful to know forces in body weights?

Answer 6

Allows you to standardise the data
Allows you to compare between people of different sizes and gives you a number that relates to their walking technique.

Question 7

What do you use a startograph board for?

Answer 7

To determine the location of COM of the body in a standing position as a percentage of the total body height.

THE POSITION OF THE COM TO BE CALCULATED IN 1 DIRECTION

Measure the distance between the two supports (d) and take the initial reading on the scale (R1)

Put the participant on the board and record (R2)

Measure the stature

Question 8

What’s the calculation for determining the position of the COM in one direction?

Answer 8

X= distance of com from pivot point
d= distance between support points
M= mass of whole body
R1= no one on board
R2= participant on board
g= acceleration due to gravity (9.81)

MgX= (R2- R1) gd
(rearrange)

X= (R2-R1) d / M