Angular Velocity and Angular Acceleration help

AI Thread Summary
In the discussion about angular velocity and acceleration, participants analyze four scenarios involving a fan's rotation. They establish that angular acceleration is positive when the fan speeds up in the counterclockwise direction and slows down in the clockwise direction. The consensus leans towards options II and III as the correct answers, indicating a clear understanding of the relationship between direction and angular acceleration. The conversation emphasizes the distinction between positive and negative angular acceleration based on rotation direction. Overall, the key takeaway is the identification of specific conditions under which angular acceleration is considered positive.
layla2525
Messages
19
Reaction score
0

Homework Statement



Consider four situations: I) a fan's rotation is speeding up while going in the clockwise direction; II) it is speeding up while going in the counterclockwise direction; III) it is slowing down while going in the clockwise direction; and IV) it is slowing down while going in the counterclockwise direction. In which cases is the angular acceleration positive?

I & II

III & IV

II & III

I & IV

Angular acceleration is always positive


Homework Equations



I know that angular counter clock wise acceleration is positive and clockwise is negative...

The Attempt at a Solution

 
Physics news on Phys.org
so what do you think the correct answer is
 
2 and 3
 
layla2525 said:
2 and 3

so like is that a guess or do you have reasons for picking those?
 

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 »

Similar threads

Angular Momentum- Conserved or not?
Replies
17
Views
422
The final velocity of a ball rolling while slipping.
Replies
40
Views
4K
Angular acceleration of plank hanging off edge with a weight
Replies
7
Views
1K
Angular velocity of a simple pendulum
Replies
2
Views
6K
Understanding Kinetic Energy, Angular Momentum & Torque
Replies
4
Views
1K
Forces when car wheels "lay rubber"
Replies
5
Views
2K
Brownian Ratchet (exercise framed by Feynman's Lectures, l. 46)
Replies
32
Views
2K
Angular momentum for a bullet and a rod attached to a ceiling
Replies
17
Views
1K
Mass, acceleration and velocity
Replies
3
Views
2K
Determine the angular acceleration and angular velocity
Replies
2
Views
3K

Hot Threads

Recent Insights

Back
Top