Question

When a gust of win blows, a decorative yard pinwheel begins to spin in a counterclockwise direction. As the wind subsides, the pinwheel slows its motion. Which of the following statements is true?

  

ω is positive and α is negative.

ω and α are both positive.

ω is negative and α is positive.

ω and α are both negative.

Answer 1

In general, angular velocity is measured in angle per unit time.

In general positive angular velocity represents counterclockwise rotation while negative is clockwise.

If angular acceleration is positive then Velocity will increase and vice versa.

Here speed decreasing so its direction is opposite as angular velocity.

So speed is counterclockwise so it's positive and angular acceleration is opposite to speed so it's negative.

Option A is correct

But generally it's upto our choice the cordinate to assume the Velocity direction. We can take negative as counterclockwise and positive as clockwise but one thing make sure is Velocity will be opposite to acceleration.

C option can also be correct .

It's upto you what you choose cordinate.

Hope you understand througly. Please upvote my hardwork and thanks