The girl in the image walks along the balance beam with her arms out to her balance. why does she do this?

So that a better balance can be obtained

Explanation:

When she lifts his arms she causes her center of gravity to rise, and the further away the center of gravity from the point of rotation (her feet), the greater the rotational inertia will be and it will swing slower allowing more time to adjust and thus be able to maintain the balance easily.

Another example of this case is when we are balancing a body in the extreme of a rod with our fingers, as we can see in the attached image.

Another example of this case is when we are balancing a body at the end of a rod with our fingers. The further the center of gravity of the rotation point (in this case the finger tip), the greater the rotational inertia and the rod will swing more slowly.

answer: electrons