Solved by a verified expert:Experiment
1 – METRIC
SYSTEM MEASUREMENTS AND CONVERSIONS
BACKGROUND:
In order to enhance commerce and science throughout the world, it is
vital that there be a standardized system of measurements and units. Actually,
there are two widely used systems.
In the U.S., we use the English system of
units; common units for length, mass, and volume are feet, slugs, and
gallons. Mass is a quantity of matter,
and is a measure of inertia. The pound, a unit in the English system that we
use for weight, is actually a force due to gravity.
In most of the rest of the world,
the metric system, known now as the International System (S.I.), is used. The
standard S. I. metric units for length and mass are the meter (m) and kilogram
(kg); the “unofficial” standard unit of volume is the liter (L). Non-standard
units are commonly used in the S.I. system (and English system), and
conversions to standard units, or vice versa, often are done. Common conversion
prefixes are: mega- = 1,000,000, kilo- = 1000,
centi- = 1/100, and milli-
= 1/1000. A further list of conversion factors is seen in the Appendix.
One milliliter is 1/1000 of a liter
and it equals one cubic centimeter (1 mL = 1 cm3). By definition,
one gram of water occupies one cubic centimeter of volume (at 4oC
(39oF)).
Some units are represented as
ratios, e.g., for density, which is defined as mass per unit of volume. A
non-standard, but commonly used S.I. unit for density is grams per cubic
centimeter, g/cm3. A common
English unit for density is pounds per cubic foot, lb/ft3. (For
example, the density of water is 62.4 lb/ft3).
OBJECTIVES:
– To learn and use the proper S. I. metric units.
– To learn how to make simple
measurements and to understand accuracy
.
– To learn
how to convert a measurement or quantity from one unit to another
PROCEDURE:
The following equipment will be
needed: meter sticks (2), bathroom scale, wood block, balance, graduated
cylinder (100 mL), graduated cylinder (25 mL), beaker (250 mL), iron nails (3).
A. Measurements
of Length
Where applicable, show all
calculations.
1.
Bench (or table) dimensions:
a.
Predict the length of your table top, in units of
meters. Then use the meter stick (or a tape measure) to verify your prediction.
Measure to the nearest centimeter, and convert to meter units (to two decimal
places (e.g., 384 cm converts to 3.84 m)).
Prediction m Table
Length cm;
__________ m
b. Measure the width of the Table top: Width cm;
__________ m
c. Calculate
the area of the Table top, using the formula:
area = length x width (A =
LW)
A = _________ m2.
2. Heights of student scientists:
a. Height Measurements. Have your height measured by someone, to the nearest
centimeter, using two meter
sticks and sliding one on the other. Record your height (in centimeters).
Your
height in centimeters cm
Convert
your height to inches (1 in = 2.54 cm) in
B. Measurements of Mass, Volume, and Density
1. Mass:
a. Weigh yourself on a bathroom
scale. lb
b. Convert the pounds to kilograms (1 kg = 2.2
lb) kg
{Each student should do
this calculation individually; show the setup}
2. Density of solids:
This procedure is useful for
measurement of the density of materials and objects that have a regular shape, e.g., a rectangular
solid, or a sphere, or a cylinder.
a.
Measure the dimensions (length, width, height) of a block of wood.
b. Calculate the volume (V) in
cubic centimeters (cm3), using the formula:
volume = length x width x height [V = L W H]
c. Using a
balance, determine the mass to the nearest 0.1 g
d.
Density is the mass per unit of volume. Using the formula for density, p
= m/V, calculate the densities
of the blocks.
mass (g) length (cm) width (cm) height (cm) Volume (cm3) density (g/cm3)
Wood
____ ______ _______ _____
_______ _______
e.
The accepted values for density of the various
materials, in units of g/ cm3, are:
wood, 0.4-0.5; aluminum, 2.7; lead, 11.4; brass, 8.6; and iron,
7.9. How does your experimental value
(EV) for the metal compare with the accepted value (AV)? That is, is it exact,
or close (slightly off), or not close (way off)?
___________________
3. Density Of Water:
a. Using the balance, weigh a 100 mL graduated
cylinder to the nearest 0.1 g.
________ g
b. Then carefully pour water
from a 250 mL beaker into the graduated cylinder,
so that the volume is close or equal to
100.0 mL.
Recordthis volume, to the nearest
0.1 mL ________
mL
c. Weighthe cylinder plus water.
________g
d. Calculate
the mass of the water (c. minus a.) ________g
e.
Calculate the volume of water, in units of cm3 ________
cm3
(Remember: 1 mL = 1 cm3).
f.
Calculatethe density of water, using the equation: p =
m/V. _________ g/cm3
(Record this value to
two decimal places)
g. The accepted value (AV) for
the density of water is 1.00 g/cm3.
Calculate the accuracy, as represented by the experimental error,
for your experimental measurement (EV) of
this density, using the equation:
Experimental Error
= 100(EV –AV)/AV =
_______ %
4. Density Of
Iron:
This procedure is useful for
measurement of the density of solid materials and objects that have an irregular shape.
a. Determine
the mass of three nails, to the nearest 0.1 g. Recordthe mass in
the table below.
b. Add
water into a 25 mL graduated cylinder to about the 18-20 mL mark. Recordthe
volume of water, to the nearest 0.1 mL.
c. Place
the three iron nails in the water. Record the new volume. The rise in
water level is equal to the volume of the nails. Calculatethis volume.
d. Now
calculate the density of iron, using the equation: p = m/V.
Mass
of iron nails __________
g
Volume of
water plus iron nails ________
mL
Volume of
water ________
mL
Volume of
iron nails
_________mL = cm3
(remember – – 1 mL = 1 cm3)
Density of
iron (p = m/V)
___________ g/cm3
The
accepted density of iron is 7.9 g/cm3. Calculate the experimental error for
your measurement of this density, using the equation:
Experimental Error =
100(EV –AV)/AV = _______ %
C. Additional Questions:
1. Why is it important to establish standard
units of measurement?
2. What are the standard units of length and
mass in the S.I. metric system?
A]
length B]
mass
3. What is the difference between mass and
weight?
4. What are two methods measuring the volume of
solids?
A] B]
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