Walking up a Hill

Calculus Level 1

Jack begins to walk up a hill at 8 a.m. and reaches the top at noon. The next day, Jack backtracks along the same path, begins to walk down the hill at 8 a.m. and reaches the bottom at noon.

True or False?

There must have been a time between 8 a.m. and noon during those two days at which Jack was at the same position on the hill.