If you cut the engines, while the Enterprise is hovering at 200 miles, she would hit the ground in 4 minutes and 16 seconds. From maximum transporter range of 16,000 miles, she would hit the ground after a leisurely 38 minutes and 11 seconds. Both times assume no atmosphere, I'm afraid I can't quite figure that out.
Twice the distance (in meters) divided by 9.81, the square root is your time in seconds.
The Captain's Log in Naked Time
said they had nineteen minutes left. But that was a while after Riley cut the engines.
There might be occasions when they're mapping a world where the ship would be in orbit.