Angular Velocity and Angular Acceleration help

[layla2525]

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

 

[SHISHKABOB]

so what do you think the correct answer is

 

[layla2525]

2 and 3

 

[SHISHKABOB]

2 and 3

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

 

[Nickie]

In all four situations, the angular acceleration is positive. This is because angular acceleration is defined as the rate of change of angular velocity, and in all four situations, the angular velocity is increasing. The direction of rotation (clockwise or counterclockwise) does not affect the sign of the angular acceleration. Therefore, the correct answer is "Angular acceleration is always positive."