**Method 3**

**Given Multiple Speeds for Different Amounts of Time**

- Assess what information you are given. Use this method if you know:
- Set up the formula for average speed.
- Determine the total distance.
- Determine the total time.
- Divide the total distance traveled by the total time spent traveling.

Similarly one may ask, what device is used to measure speed?

List of measuring devices

Device | Quantity measured |
---|---|

sextant | location on earth's surface (used in naval navigation) |

spectrometer | properties of light |

spectrophotometer | intensity of light as a function of wavelength |

speedometer | speed, velocity of a vehicle |

What tool measures speed?

The

**speed**of that wind can be measured using a**tool**called an anemometer. An anemometer looks like a weather vane, but instead of measuring which direction the wind is blowing with pointers, it has four cups so that it can more accurately**measure**wind**speed**.How do we measure the speed of light?

The

**speed of light**in a vacuum stands at “exactly 299,792,458 metres per second“. The reason today**we**can put an exact figure on it is because the**speed of light**in a vacuum is a universal constant that has been measured with lasers; and when an experiment involves lasers, it's hard to argue with the results.