Angular Momentum: Formula Comparison & Usage

AI Thread Summary
Two formulas for calculating angular momentum are discussed: L = r x p for point particles and L = Iw for objects rotating about a fixed axis. The first formula applies to point particles, while the second is suitable for extended objects, such as a rod rotating around one of its ends. It's important to ensure that the moment of inertia (I) corresponds to the object and axis in question. Understanding when to use each formula is crucial for accurate calculations. Proper application of these formulas is essential for analyzing angular momentum in various physical scenarios.
grief
Messages
73
Reaction score
1
I have two formulas to find angular momentum, and I am not sure when to use one and when to use the other, or what the difference is between the two. One is L = r x p, and the other is L=Iw.
 
Physics news on Phys.org
The former is used for a the angular momentum of point particle about some point, while the latter is used for the angular momentum of an object rotating about a fixed axis.
 
Last edited:
ok, I understand now. Thanks
 
so, if it's a rod, for example, rotating about one of its ends, I should use L=Iw?
 
Given that a rod is not a point particle, yes.

Just be careful to note that the moment of inertia (I) you are using is for that object about the given axis.
 

Thread 'Rolling without slipping on a curved surface'

Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
View full post »

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'A bead-mass oscillatory system problem'

Thread 'A bead-mass oscillatory system problem'

I can't figure out how to find the velocity of the particle at 37 degrees. Basically the bead moves with velocity towards right let's call it v1. The particle moves with some velocity v2. In frame of the bead, the particle is performing circular motion. So v of particle wrt bead would be perpendicular to the string. But how would I find the velocity of particle in ground frame? I tried using vectors to figure it out and the angle is coming out to be extremely long. One equation is by work...
View full post »

Similar threads

Angular Momentum- Conserved or not?
Replies
17
Views
445
Angular momentum for a bullet and a rod attached to a ceiling
Replies
17
Views
1K
Angular Momentum Problem: Mouse walking on a rotating turntable
Replies
5
Views
1K
Conservation of Angular Momentum -- Child jumping onto a Merry-Go-Round
Replies
18
Views
6K
System of two wheels of different sizes with an axle through their centers
2
Replies
67
Views
4K
Conservation of angular momentum under central forces
Replies
4
Views
2K
Collision of a bullet on a rod-string system: query
2
Replies
71
Views
2K
Angular momentum of a disk about an axis parallel to center of mass axis
Replies
5
Views
3K
How Does Angular Momentum Conservation Affect Asteroid Collision Dynamics?
7
Replies
335
Views
14K
Problem in understanding angular momentum of a rigid body
Replies
10
Views
2K

Hot Threads

Recent Insights

Back
Top