linear motion

Question 1

letters for SUVAT

Answer 1

S = displacement
U = intial velocity
V = final velocity
A = acceleration
T = change in time

Question 2

pros of embedded force plate

Answer 2

-accurate and reliable 3D force measurements
-high sampling frequency + resolution

Question 3

cons of embedded force plate

Answer 3

-ecological validity (cannot recreate outside activity)
-expensive

Question 4

portable force platform pro and con

Answer 4

:) cheaper
:( slightly worse reliability, validity, resolution

Question 5

pros of triaxial accelerometer

Answer 5

measure instantaneous acceleration

Question 6

comment on triaxial accelerometer

Answer 6

need to know what you’re using it for in order to assess whether it is reliable and valid

Question 7

pros of accelerometer position

Answer 7

-cheaper than lab based equipment
-easy to use

Question 8

cons of acclerometer position

Answer 8

-battery life
-does it affect the movement being monitored?

Question 9

impulse is the

Answer 9

change in momentum

Question 10

impulse (Ns) equation

Answer 10

force (N) x time (secs)

Question 11

moments can sometimes be called

Answer 11

torques

Question 12

moment equation =

Answer 12

force x perpendicular distance

Question 13

friction is …

Answer 13

a force that acts in opposition to the movement of one surface over another

Question 14

friction equation =

Answer 14

coefficient of friction x normal force

Question 15

name the three types of friction

Answer 15

static, sliding, rolling

Question 16

the coefficient of friction is between 0 and 1, what does closer to 1 mean?

Answer 16

closer to 1 = more friction
closer to 0 = less friction

Question 17

why is static friction higher than dynamic friction?

Answer 17

because it is harder to start something moving than it is to keep something moving

Question 18

what is air/water resistance?

Answer 18

the friction of something moving through something

Question 19

equation for drag force FDRAG

Answer 19

0.5 p v2 Cd A

Question 20

what do the letters stand for in the drag force equation

Answer 20

p = density of the fluid
v = relative velocity squared
Cd = drag coefficient
A = surface area

Question 21

what will happen if relative velocity is doubled?

Answer 21

drag force is x4 quadrupled (because velocity is squared)

Question 22

how to calculate velocity in opposite directions

Answer 22

the sum (add +)

Question 23

how to calculate velocity in the same direction

Answer 23

the difference (minus -)

Question 24

the higher the drag coefficient …

Answer 24

the more drag force there is

Question 25

LAMINAR air flow

Answer 25

-fluid slides smoothly
-layers flow in parallel
-little disruption to fluid

Question 26

TURBULENT air flow

Answer 26

-slows objects
-boundary layer composed of vorticles that increase friction
-more disruption

Question 27

turbulant flow causes

whereas laminar flow

Answer 27

more friction

causes less resistance to movement

Question 28

methods of reducing drag

Answer 28

-more streamlined shape -> to change your drag coefficient

-smaller surface area -> to reduce the amount of drag

-slower relative velocity -> in drafting (e.g., cycling)

Question 29

greater relative velocity means that there is

Answer 29

-> more disturbance of the fluid around the object
-> have to work harder to overcome fluid forces