PART II – CHOOSING THE APPROPRIATE UNIT For each example below choose the appropriate unit to measure each (mm, cm, m or km). 1. Width of physics book 2. Distance from New York to Utah 3. Length of fingernail 4. Length of hallway 5. Height of a mountain 6. Length of a fork 7. Distance between cities 8. Width of your eyeball

Explanation:

In this unit of measurement for distance or length, the units are arranged from the least to the largest unit i.e

mm < cm < m < km

Where mm is millimeter, cm is centimeter, m is meter and km is kilometer.

Hence, the appropriate unit to be used depends on how small or wide the length/distance being referred to is. For instance, the length of a stapler pin should be measured in millimeter while the length of a pen should be measured in centimeter. The appropriate measurement can be determined by determining the closest unit the value falls into. For instance, there is no need to refer to a length as 1000 cm when it can be referred to as 10 m (since 100 cm equals 1 m)

1. Width of a physics book should be measured in centimeters (this is similar to length of a pen).

2. Distance from New York to Utah should be measured in kilometers (Distance between far cities or states are measured in kilometers).

3. Length of a fingernail should be measured in millimeters (this is similar to the length of a stapler pin)

4. Length of hallway should be measured in meters (This is generally larger than centimeter but lesser than kilometer)

5. Height of a mountain should be measured in kilometers (This is usually a very long distance from the earth surface)

6. Length of a fork should be measured in centimeters (This is similar to the length of a pen).

7. Distance between cities should be measured in meters (except the distance is far apart, distance between close cities are measured in meters)

8. Width of the eyeball should be measured in millimeters (similar to the length of a stapler pin and fingernail).

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray