Hi, I'm new to the forum, and loathe to admit that I'm well out of high school and have the mathematical knowledge of a snowpea. Can anyone help me with the following scenario? A person drops down a 200 ft. vertical shaft. Now underground, they will travel through a tunnel at a downward slope until they reach a depth of 1 and 1/2 miles. My question is, how steep do I need to make my slope? Since they are walking, it would need to be shallow enough that they can comfortably remain upright, but also steep enough that they will reach their target depth within 1 hour, 2 hours if it's more logical. I appreciate any help you guys can give me!