The hardness of common objects are listed in the table. if an unknown mineral cannot be scratched by glass but can be scratched by a steel file, what might its hardness be?

meteorologists would compare a new weather map with one 24 h old to see how fast a front is moving.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.