| Questions | 5 |
| Topics | Atomic Mass, Base Units, Light Waves, Medulla, Outer Planets |
The atomic mass of an element listed in the Periodic Table represents the average mass of a single atom of that element and is measured in atomic mass units (amu). This number is an average as some elements have isotopes with atoms that vary in their number of neturons and, therefore, differ in weight.
| Measurement | Base Unit | Example |
|---|---|---|
| length / distance | meter (m) | km |
| mass | gram (g) | kg |
| volume | liter (L) | mL |
| volume (medical) | cubic centimeter (cc) | cc |
| time | second (s), minute (min), hour (h) | ms, min, h |
| temperature | centigrade (°C) | °C |
Unlike mechanical sound waves that require a physical medium for propagation, light waves are electromagnetic and can travel through empty space. Light waves are also much faster, travelling at 186,000 m/s vs. 343 m/s for sound waves.
Part of the brainstem, the medulla is the connection between the brain and the spinal cord. It controls involuntary actions like breathing, swallowing, and heartbeat.
In contrast to the solid terrestrial planets, the outer planets (Jupiter, Saturn, Uranus, and Neptune) consist of hydrogen and helium gas and water.