Engineering - Rotational Dynamics

Question 1

Define angular displacement

Answer 1

Angle turned through

Question 2

Define angular velocity

Answer 2

Rate of change of angular displacement

Question 3

Define angular acceleration

Answer 3

Rate of change angular velocity

Question 4

How is angular acceleration determined for a rotating object that changes angular speed?

Answer 4

Angular version of suvat

Question 5

How is speed and acceleration at a point on a rotating object worked out?

Answer 5

Angular version multiplied by radius

Question 6

Angular displacement against time graph, what is gradient?

Answer 6

Angular velocity

Question 7

Angular velocity against time graph, what is gradient and area under?

Answer 7

Gradient: angular acceleration

Area under: angular displacement

Question 8

Define torque

Answer 8

Force times perpendicular distance from the axis to the line of action of the force

Question 9

Define inertia

Answer 9

An object’s resistance to change of its motion

Question 10

What is the moment of inertia?

Answer 10

Moment of inertia, I, of a body about a given axis is defined as Σmr^2 for all the points in the body, where m is the mass of each point and r its perpendicular distance from the axis

Question 11

For a hoop of mass M and radius R, what is the moment of inertia?

Answer 11

MR^2

Question 12

For a disc of mass M and radius R, what is the moment of inertia?

Answer 12

1/2 MR^2

Question 13

For a uniform beam of length L and mass M, what is the moment of inertia through its centre?

Answer 13

1/12 ML^2

Question 14

For a uniform beam of length L and mass M, what is the moment of inertia through its end?

Answer 14

1/3 ML^2

Question 15

What is the kinetic energy of a rotation object proportional to?

Answer 15

Moment of inertia about axis of rotation

Square of its angular speed

Question 16

How can moment of inertia for a fly wheel be calculated?

Answer 16

Using 1/2 (Iω^2 + Mv^2) = Mgh

Question 17

What is angular momentum?

Answer 17

Produce of moment of inertia and angular velocity

Question 18

What is torque in relation to angular momentum?

Answer 18

Torque is rate of change of angular momentum

Question 19

Define angular impulse

Answer 19

Change in angular momentum

Question 20

Define conservation of angular momentum

Answer 20

I1ω1=I2ω2