Lecture 21 - Angular Kinetics : Mass Moment of Inertia

Question 1

locating the centre of mass is directly related to torque in that …

Answer 1

a force directed through the centre of mass should cause linear motion only.

Centre of mass is located at a point where the sum of torques = 0

Question 2

what is the equation for angular acceleration

Answer 2

a = T / mr^2

Question 3

why is mass called inertia in the acceleration equation

Answer 3

it is the resistance to move

Question 4

angular acceleration is the resistance to rotate is related to ..

Answer 4

resistance to rotate is related to mass and the distribution of mass around the axis of rotation

Question 5

in angular acceleration, if the radius is reduced then

Answer 5

the effect of the torque is greater so therefore there will be greater angular acceleration

Question 6

in angular acceleration if we increase mass by 2 we

Answer 6

decrease acceleration by 2

Question 7

in angular acceleration if we increase the radius by 2 we

Answer 7

decrease acceleration by 4

Question 8

what is the equation for mass moment of inertia

Answer 8

I = mr^2

Question 9

what is the radius of gyration

Answer 9

describes how an object’s mass is distributed relative to an axis of rotation

Question 10

what is total inertia equal to, if the object rotates about an axis that is not the centre of mass

Answer 10

I = Icm + mk^2

Question 11

total inertia =

Answer 11

local inertia + remote inertia

Question 12

what is the parallel axes theorem

Answer 12

I(tot) = Icm + mk^2

Question 13

the radius of gyration is a term used when we are dealing with

Answer 13

segmented masses where the axis of rotation is not located through the centre of mass

Question 14

for airborne rotating mass we have a total moment of inertia that is the sum of

Answer 14

the local (Icm) and remote (mk^2) terms