6.6.1 The Definition of Angular Momentum

Question 1

The Definition of Angular Momentum

Answer 1

• Angular momentum is the rotational analogue of linear momentum. It is defined as .
• The angular momentum of a rigid body rotating about a fixed axis of symmetry is given by .

Question 2

For an object rotating on a massless rod (as seen in the diagram below), which of the following formulas could be used to calculate the magnitude of its angular momentum?

Answer 2

• L = rmv
• L = mr^2w
• L = Iw

Question 3

Two objects with masses m1 and m2 rotate on a turntable with a moment of inertia IT. Which of the following describes the magnitude of the total angular momentum of the system

Answer 3

L = ITw + mr1^2w + mr2^2w

Question 4

Two objects with masses m1 and m2 rotate about a fixed point on massless rods as shown in the diagram below. Which of the following equations describes the magnitude of the total angular momentum of the system?

Answer 4

L = r1m1v1 - r2m2v2

Question 5

What is the direction of the angular momentum of the object in the diagram. Bothj r and v are in the xy-plane

Answer 5

Down along the z-axis

Question 6

Two masses rotate around their center of gravity on the ends of a massless rod, as shown in the diagram below. This system has which of the following kind(s) of momentum?

Answer 6

Only angular momentum

Question 7

Which of the following diagrams correctly describes the radius arm of the angular momentum of the object?

Answer 7

-

Question 8

In the following diagram, how do we calculate r?

Answer 8

r = rsin theta

Question 9

For which of the following figures is the equation L = Iw not applicable?

Answer 9

-

Question 10

Which of the following states why the following sentence is meaningless? “Find the angular momentum of a falling object of mass m after falling from rest for a time t.”

Answer 10

Angular momentum is always relative to a specified origin.