Transcript DENSITY.ppt

DENSITY
Concepts to explain
DENSITY.
 Density- the Mass of an object divided
by it’s Volume.
 Formula: Density = Mass/ Volume or
D=M/V
 Units: g/cm3 or g/ml
 The units used is dependent on how you
got your Volume.
 USE THE TRIANGLE TO WORK
DENSITY PROBLEMS!
Sample Problems
 Raven measured the Mass of a rock on
the Triple Beam Balance. She found it to
be 5 grams. She then measured the
Volume in a Graduated Cylinder. Her
initial Volume was 20 ml and her final
Volume was24 ml. What is the Density of
the Rock?
 D=? M=5g V=4ml
D=M/V=5g/4ml=1.25g/ml
Things to Know
 If an object has a Density GREATER THAN
1g/ml or 1g/cm3, then it will SINK in Water!
 If an object has a Density LESS THAN 1g/ml or
1g/cm3, then it will FLOAT in Water.
 Density is a characteristic material property;
thus the Density of two objects of the same
material is always the same even if the masses
of the two objects are different.
Problems for You to
Master
 A wooden cube is measured at 2cm on
one side. It has a mass of 4g. What is
it’s Density and what will it do in H2O?
 A marbles’ mass is 10g and when it’s
volume was measured the initial volume
was 25ml with a final volume of 32ml.
Calculate the Density and describe what
will happen when placed in water?
Density Quiz
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D=? M=6g V=3ml
M=? D=5g/cm3 V=5cm3
V=? D=.75g/ml M=2g
Find the mass of an object with a Density
of 1.5g/cm3 and a Volume of 2cm3.
 What is the Density of a steel ball that
has a mass of 20g. It was placed in a
graduated cylinder with an initial Volume
of 20ml and a final Volume of 35ml?
SCIENTIFIC NOTATION
Scientific Notation- expresses a number as the
coefficient times a base of ten raised to a
power or exponent, which is expressed as:
power
Coefficient (Base) X10
where the exponent equals the number of
decimal places in the original number.
Use of Scientific Notation
 Scientific Notation simplifies very large or
very small numbers that have many
zeros. These large or small numbers are
said to be in STANDARD FORM.
Example: 5,947,398,021Km (Large)
.0000002963dg (Small)
Writing in Scientific
Notation
In the first example; 5,947,398,021 you have to
place the decimal behind the first whole
number (coefficient) to get 5.94, next the base
is ALWAYS times ten (X10), and the exponent
(power) represents the number of places the
decimal was moved to get the base. The result
should be as follows:
9
5.94 X10
SAMPLE PROBLEMS
Convert from Standard Form to Scientific
Notation:
12,300=
304,000=
1,083,000,000,000=
6,200=
124=
Converting from Scientific
Notation to Standard Form
To convert from Scientific Notation to
Standard Form you must do the reverse
by moving the decimal in the opposite
direction. Example:
5
3.07 X10 = 307,000 In this example
move the decimal 5 places to the right
and add zeros.
Small Numbers and
Scientific Notation
If the Standard Form number is LESS THAN 1
(one), then you must use a NEGATIVE
exponent (power). All other rules still apply
with the exception of the direction that the
decimal is moved. Example:
-7
.0000002963 = 2.96 X10
Reverse the
process when going from Scientific Notation to
Standard Form.
More Sample Problems
Working with small numbers:
.00047 =
.000000100045 =
.035400 =
-5
2.3 X10 =
-3
5.48 X10 =
Calculations with
Scientific Notation
 ADDITION and SUBTRACTION
1. Express the numbers as the SAME
exponential (power) of 10.
2. Add or Subtract the coefficient.
3. Express the answer in correct scientific
notation.
Example:
23,435,005 + 5,689,023 = ?
6
6
6
23.4 X 10 + 5.6 X 10 = 29.0 X 10
More Calculations with
Scientific Notation
 MULTIPLICATION:
1. Multiply the coefficients.
2. Add the exponents.
3. Express answer in scientific notation.
Example:
4
3
7
(3 X10 ) X (4 X10 ) = 12 X10
Some More Calculations
with Scientific Notation

1.
DIVISION:
Change the sign of the exponent in the denominator
(place circle around the change).
2. Combine the exponents.
3. Divide the coefficients.
4. Express answer in scientific notation.
Example:
6
6
36 X10
36 X10
3
3 =
-3 =
6 x10
6 X10
6 X10