Understand the analogy between angular momentum and linear momentum.
Observe the relationship between torque and angular momentum.
Apply the law of conservation of angular momentum.
The information presented in this section supports the following AP® learning objectives and science practices:
4.D.2.1 The student is able to describe a model of a rotational system and use that model to analyze a situation in which angular momentum changes due to interaction with other objects or systems.
(S.P. 1.2, 1.4)
4.D.2.2 The student is able to plan a data collection and analysis strategy to determine the change in angular momentum of a system and relate it to interactions with other objects and systems.
(S.P. 2.2)
4.D.3.1 The student is able to use appropriate mathematical routines to calculate values for initial or final angular momentum, or change in angular momentum of a system, or average torque or time during which the torque is exerted in analyzing a situation involving torque and angular momentum.
(S.P. 2.2)
4.D.3.2 The student is able to plan a data collection strategy designed to test the relationship between the change in angular momentum of a system and the product of the average torque applied to the system and the time interval during which the torque is exerted.
(S.P. 4.1, 4.2)
5.E.1.1 The student is able to make qualitative predictions about the angular momentum of a system for a situation in which there is no net external torque.
(S.P. 6.4, 7.2)
5.E.1.2 The student is able to make calculations of quantities related to the angular momentum of a system when the net external torque on the system is zero.
(S.P. 2.1, 2.2)
5.E.2.1 The student is able to describe or calculate the angular momentum and rotational inertia of a system in terms of the locations and velocities of objects that make up the system. Students are expected to do qualitative reasoning with compound objects. Students are expected to do calculations with a fixed set of extended objects and point masses.
(S.P. 2.2)
Why does Earth keep on spinning? What started it spinning to begin with? And how does an ice skater manage to spin faster and faster simply by pulling her arms in? Why does she not have to exert a torque to spin faster? Questions like these have answers based in angular momentum, the rotational analog to linear momentum.
By now the pattern is clear—every rotational phenomenon has a direct translational analog. It seems quite reasonable, then, to define
angular momentum
as
This equation is an analog to the definition of linear momentum as
. Units for linear momentum are
while units for angular momentum are
. As we would expect, an object that has a large moment of inertia
, such as Earth, has a very large angular momentum. An object that has a large angular velocity
, such as a centrifuge, also has a rather large angular momentum.
Making connections
Angular momentum is completely analogous to linear momentum, first presented in
Uniform Circular Motion and Gravitation . It has the same implications in terms of carrying rotation forward, and it is conserved when the net external torque is zero. Angular momentum, like linear momentum, is also a property of the atoms and subatomic particles.
Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
_Adnan
But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
Elkana
This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
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_Adnan
define infection ,prevention and control
Innocent
I think infection prevention and control is the avoidance of all things we do that gives out break of infections and promotion of health practices that promote life
