When is angular acceleration positive for a rotating fan?

[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?