RHYMING RIDDLES

1)
They wait in line to ride on me,
And do so voluntarily;
They know before they depart
They'll end up back where they start.
For those brave souls who seek a thrill,
I'm sure to nicely fit the bill;

My start is slow, and truth to tell,
To rely on a machine I'm compelled;
But once I start my downward dell,
By a force of nature I'm propelled.
At my start do many fret,
But seldom exit with regret.

2)
Through my first forever flow
Sounds of laughter, sounds of woe;
Words of every sort and kind,
Enter here to reach my mind.
My second is often found in a tree,
Where new-born life you may see.
In my whole, men never jest,
Vows are uttered, sins confessed.

Answer:

1. Roller coaster 
2. EARNEST  (EAR + NEST)