Use the adjective mechanical to describe something related to machinery or tools. If your car breaks down on the same day that your watch stops, you've got a lot of mechanical problems.
You’ll most often hear mechanical used to describe something involving a machine. A mechanical problem at work might mean the copier has broken down again. Mechanical can also refer to physical forces, called mechanics having to do with how things move, like the mechanical elegance of a pendulum. We also use mechanical for human things that are so tedious, repetitive or automatic that they feel like they're done by machines and not people.