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Welcome to our Physics lesson on Angular Momentum, this is the fifth lesson of our suite of physics lessons covering the topic of Dynamics of Rotational Motion, you can find links to the other lessons within this tutorial and access additional physics learning resources below this lesson.
Angular momentum, L, is a vector quantity (more precisely, a pseudo-vector) that represents the product of a body's rotational inertia and rotational velocity (in radians/sec) about a particular axis. It is the equivalent of momentum in linear motion.
Mathematically, we can write
The unit of angular momentum is [kg × m2 / s].
What is the angular momentum of Earth when revolving around itself? Take the following approximate values: MEarth = 6 × 1024 kg, REarth = 6400 km and TEarth = 86400 s.
Earth can be considered as a solid sphere. Therefore, its moment if inertia is
We have, R = 6400 km = 6 400 000 m = 6.4 × 106 m. Also, m in the formula is replaced by M as Earth has a very large mass. Hence, we can write:
Now, let's calculate the angular velocity of Earth. Since for one revolution φ = 2π and t = T, we have
Hence, Earth's angular momentum is
You have reached the end of Physics lesson 7.2.5 Angular Momentum. There are 8 lessons in this physics tutorial covering Dynamics of Rotational Motion, you can access all the lessons from this tutorial below.
|Tutorial ID||Physics Tutorial Title||Tutorial||Video|
|7.2||Dynamics of Rotational Motion|
|Lesson ID||Physics Lesson Title||Lesson||Video|
|7.2.1||Moment of Force as Analogue of Force in Translational World|
|7.2.2||Moment of Inertia|
|7.2.3||Moment of Inertia in Different Systems of Rotational Motion|
|7.2.4||Newton's Second Law for Rotational Motion|
|7.2.6||Work in Rotational Motion|
|7.2.7||Kinetic Energy in Rotational Motion|
|7.2.8||Power in Rotational Motion|
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