Y2 Equations

Question 1

1 radian = how many degrees?

Answer 1

57.3 degrees (180/pi)

Question 2

Displacement

Answer 2

difference between initial and final position

Question 3

Angular Velocity

Answer 3

change in angular position/change in time

Question 4

Angular Speed

Answer 4

angular distance/time

Question 5

Angular Acceleration

Answer 5

change in ang velocity/time

Question 6

First Central Difference Method

Answer 6

v = (positionfinal – positioninitial)/ (timefinal – timeinitial)

Question 7

Angular Motion

Answer 7

Vt = r x w
Vt = linear/tangential velocity
R= length of radius
W= angular velocity

Question 8

Moment

Answer 8

M= force x distance

Question 9

Inertia Definition

Answer 9

objects tendency to resist a change in motion

Question 10

Force

Answer 10

F =m x a

Question 11

Resultant force

Answer 11

mres= m1 +m2

Question 12

Reaction Board

Answer 12

length of board (r2-r1) /weight

Question 13

Segmental Method

Answer 13

MgX = E(MiGxi) 
MgY= E(MiGyi)

Mi= segment mass
XiYi= coordinates of segment CoG
M= total body mass
XY= coordinates of body CoG

Question 14

Inertia

Answer 14

I= E(mass x distance to axis of rotation2)

 Human’s inertia values are ~10

Question 15

Segment Moment of Inertia

Answer 15

IA = Icg + md2

IA= Moment of inertia of body rotating, at centre of gravity
ICG- Moment of inertia of segment about its cog
MD2 = mass of segment x distance2 between segment cog and whole body cog

Question 16

Pendulum Technique

Answer 16

I = (MghT^2)/4πr
I= inertia 
M=mass of subject
T= time for one oscillation
H= distance of mass centre from axis of suspension

Question 17

Angular Momentum

Answer 17

H = IW
H=angular momentum
I= Inertia
W-angular velocity

Question 18

Angular Momentum, about a given axis

Answer 18

Hs= IsWs/Gs + Msr2WGs/G
Is= segment inertia about axis through the segment cofg
Ws/Gs = angular velocity of the segment about axis through Gs
Ms= mass of segment
R= distance between body cofg and segment cofg
WGs/G= angular velocity of segment cofg about transverse axis, through body cofg

Question 19

Newtons 1st Law

Answer 19

A rotating body will continue to rotate with a constant angular momentum unless acted upon by an external moment.

Question 20

Newtons 2nd law

Answer 20

An external moment produces an angular acceleration that is:

• proportional to the moment
• in the direction of the moment

Question 21

Moment (angular acceleration)

Answer 21

EM = Iα
M= moment
I= inertia
α= angular acceleration

Question 22

Moment (force)

Answer 22

Moment = force x distance

Question 23

Newtons 3rd Law

Answer 23

For every moment exerted by one body on another, there is an equal opposite moment exerted by the second body on the first.