Finding Angular Displacement in a Pirouette

[Spartan301]

Hey, I have a very easy problem.

A dancer completes 2.2 revolutions in a pirouette. What is her angular displacement?

here's my work.
Given:
2.2 revolutions.

Battle Plan:
Find angular position in radians.
Subtract final position with the initial position.

Outcome:
2.2 x 2pi = 4.4 pi radians
=13.823
sig figs: 2
=14 rad

The key says 14 rads is correct, but I'm confused because I thought that you had to subtract the final position from the initial position.

If I did that to find the true angular displacement, wouldn't it be something like 0.4 rads?

Does my math look correct, or is there a concept I'm missing?

Thanks so much.
-Tom

 

[SammyS]

The initial angular displacement is zero.

 

[Spartan301]

The initial angular displacement is zero.

Certainly. But she passes 0 two times. After that she only rotates for about 0.2 revolutions, right? Wouldn't that be the angular displacement instead?

-Tom