Lab1 Metric Scientific Method

LAB 11. The Metric System
West Los Angeles College
Fall 2008
Biology 3

Internationally agreed set of units for measurement of length, mass and weight.
Advantages: Measurements are stable, reproducible and easily made (easy conversions).
All units are based on multiples or divisions of 10, ie it’s a “decimal system”.
The basic units are meter, liter and gram

Meter
Basic unit of length
Abbreviation: m
1 meter is a bit longer than a yard.
Conversion from English to Metric:
1 inch = 2.54 cm
1 foot = 0.30 m
1 yard = 0.91 m
1 mile = 1.61 Km

Liter
Basic unit of volume
Abbreviation: l
1 liter is slightly larger than a quart.
1 pint = 0.47 l
1 quart = 0.96 l
1 gallon = 3.79 l
1 Tbp = 0.02 l

Gram
Basic unit of mass or weight
Abbreviation: g
1 gram is a small measure, similar to the weight of a paperclip.
1 gram = 0.035 oz
1 oz. = 28.35 g
1 pound = 454 g

Metric System = Decimal system
multiples or divisions of 10, so it can also be expressed in powers of 10.
102 means there are 2 zeros after the 1 or 100
10-2 means there are 2 zeros before the 1 or 0.01
The difference between 102 and 10-2 is 104,
2-(-2) = 4 meaning 4 zeros after the 1, ie 10 000.

A few things to remember…. (1)
If the original number is less than 1, the exponent is negative (-),
if the original number is greater than 1, the exponent is positive (+).
OR
If you moved the decimal to the right, the exponent is negative(-),
if you moved the decimal to the left, the exponent is positive (+).
0.00105 = 1.05 x 10-3
1,050 = 1.05 x103
1 2 3
3 2 1

A few things to remember…. (2)
if there is no decimal in the number, it is after the last digit
1,050 = 1050.0
all zeroes after the last non-zero digit to the right of the decimal can be dropped
1.050 = 1.05
all simple numbers less than 1 are written with a zero to the left of the decimal
.105 = 0.105

Metric units that are greater or smaller than the basic unit by a factor of 10 are named by adding prefix to the basic unit name. You need know (i.e., memorize) what each metric prefix represents.

Converting units within the metric systemWhen going from smaller tolarger unit of measure
Work with the exponent
Subtract the power of 10 of the larger unit from the power of 10 of the smaller unit
The difference signifies the numbers of place you must move the decimal
Move the decimal point to the left.
Example:
105 mg (105 x10-3g) = ____ kg (? x103g)
(-3) – 3 = -6
105 mg (105 x10-3g) = 0.000105kg (0.000105 x103g)

Converting units within the metric systemWhen going from larger to smaller unit of measure
Work with the exponent
Subtract the power of 10 of the larger unit from the power of 10 of the smaller unit
The difference signifies the numbers of place you must move the decimal
Move the decimal point to the right.
Example:
105 kg (105 x103g) = _____ mg (? x10-3g)
(3) – (-3) = 6
105 kg (105 x103g) = 105,000,000mg (105,000,000 x10-3g)

Practice
Convert:
1 m =Km
1 ml =dl
1 mm =μm
1 cm =mm
100 ml=l
10 dm=μm
10 ml=l
1.3 m=mm
1 μm =nm
100,000ng =g
15 dl =l
2.5cm =m
8 g =μg
63 mm=m
0.65 l=ml
16 mg =μg

1 foot  30 cm
3.5 feet X cm
Converting Between Metric and English Systems
Example: Converting 3.5 feet into cm
We know that 1 foot = 0.3 m = 30 cm
1 foot xX cm = 30 cm x 3.5 feet
X cm = 30 x 3.5 = 150 cm
1

Practice
Convert:
2 pint =l
4.6 oz = g
2.1 pound =Kg
6 yards =m
26.2 miles =Km
66 feet =m
8.2 in =cm