Answer:
When Earth was still molten, gravity pulled dense elements down to Earth's center.
Explanation:
Have a Good day!! :)
<span>longitudinal waves traveling along the horizontal direction </span>
All you have to do is set your mind to it. Just think do you really want it done? If yes then that is your motivation. If no then it´s hopeless. Try to find a fun way to do the activity or whatever is that your procastinating from. I hope this helps. Keep in mind, It´s on you!