1. A piston in an airtight pump is withdrawn so that the volume of the air chamber is increased three times. What is the change in pressure?
2. A scuba diver breathes compressed air beneath the surface of water. If for some reason she abandons her scuba gear and returns to the surface while holding her breath, what happens to the volume of her lungs?
1. The pressure in the piston chamber is reduced to one-third. This is the principle that underlies a mechanical vacuum pump.
2. As she rises the surrounding water pressure on her body decreases, which allows the volume of air in her lungs to increase—ouch! A first lesson in scuba diving is to not hold your breath when ascending. To do so can be fatal.