Question

When a spinning star shrinks in radius, it speeds up. Which of the following statements explains this phenomenon?

Answer 1

Answer:

B.)Angular momentum is always conserved

Explanation:

Angular momentum is given by:

$L=mvr$

where

m is the mass of the object

v is its speed

r is the distance between the object and the centre of its circular trajectory

In absence of external torques, angular momentum is always conserved. That means that for the spinning star, if its radius r decreases (because it shrinks), in order for L (the angular momentum) to be conserved, the speed (v) must increases, therefore the spinning star speeds up.

So, the correct choice is

B.)Angular momentum is always conserved