He reasoned that since parallax could not be observed for celestial objects near the sun, then the earth was stationary. This erroneous assumption was because at the time he had no way of knowing that celestial objects were so far away that their parallax angles were too small to detect.
Answer:
The acceleration of Abbie is half of the Zak's.
Explanation:
The centripetal acceleration of an object on a circular path is given by :

Two children are riding on a merry-go-round that is rotating with a constant angular speed. Let
is distance of Abbie from the merry-go-round and
is distance of Zak's from the merry-go-round. Acceleration of Abbie is :
...... (1)

Acceleration of Zak's is :
.......(2)

Dividing equation (1) and (2) we get :

So, the acceleration of Abbie is half of the Zak's.
Earth's inner core is solid even though the temperature is so high because the pressure is also very high.
Hope this helped:)