PHYSICS 1 LECTURE
SCIENTIFIC NOTATION:
-
Method of writing very large and very small
numbers as multiplication with integer power of 10.
Example: 267,000,000 in scientific notation is 2.67 x 108
0.00000493 in scientific notation is 4.93 x 10-6
RULES in
writing scientific notation:
1.
The coefficient must be 1 or greater but less
than 10 ; there must be 1 non zero whole number digit
2.
. The base is always 10
3.
The exponent must be a positive or negative
integers
Note:
LARGE
NUMBER are written with positive
exponent
SMALL
NUMBER are written with negative exponent
MEASUREMENT
ENGLISH
SYSTEM:
-
Traditionally used in US
-
Slowly being replaced by the metric system
-
Example are inch, yard, miles for distance,
pint, quartz and gallon for volume, ounce, pound, weight for weight.
METRIC
SYSTEM:
-
Units used for scientific measurement
-
First developed in France during the late 18th
century
-
Use prefixes to indicate different power of 10
-
Examples are meter, gram, liter
THE
INTERNATIONAL UNIT OF MEASUREMENT
-
Specific choice of metric unit for uses in
scientific measurement
-
Its unit are called SI unit from its acronym in
French “Systeme International d Unites”
SI BASE UNIT
·
FUNDAMENTAL UNITS were other units are derived
DERIVED SI UNIT
·
Units derived form the SI base unit
Other:
Velocity
=
m/s
Acceleration
= m/s2
Special
SI Unit:
Force
= N or kg m/s2 (Newton)
Energy/Work = N-m
(Joule)
Power
= J/s = (Watt)
UNCERTAINTY IN MEASUREMENT
1.
Exact Number
Those number that are known exactly
Example:
No of
count noun
3
ballpen, 10 student, 15 teachers
2.
Inexact numbers
Those numbers whose value has some uncertainty
Ø
Number obtained by measurement
Ø
Very large number even if they represent count
noun
o
No, of voters in the Philippines
SIGNIFICANT
FIGURES
Ø
These method which the scientist represent the
accuracy of the measuring instrument used to obtain the measured data.
Rules in
determining the no. of significant figure
1.
Exact number are considered to have an infinite
number of significant figures
Ex.
5 mangoes 3 banana 15 students
2.
All non zero digits are significant
3.
Zeroes between two non zero digits are
significant
4.
Zeroes at the right end of the number and the
right place of the decimal are significant
5.
Zero to the left of the leftmost non zero digits
are not significant
6.
If a number is written in scientific notation,
its significant digit are the significant digits in tts coefficient.
7.
Zeroes at the right end of the number and left
of decimal place may or may not be significant. To remove the ambiguity, write
the number in scientific notation
CONVERSION
STEPS IN CONVERTING UNITS
1.
Determine which units must be replaced and what
unit will replace it
2.
Write the unit equivalence in fractional form
3.
Multiply the units with the conversion faction.
Example:
1.
Convert
2500g to kg
Steps:
Det. The unit to be replace , g to
kg
Det. The given GIVEN =
2500g
Det. The conversion Factor
Conversion factor
: 1000g = 1kg
Therefore the CF is
written in fractional form CF
= 1kg/1000g (g is on denominator since
it is the unit to be replaced)
Multiply the given with the conversion
factor (CF)
kg = 2500g
x
1kg/1000g (note g will be
cancelled)
kg
= 2.5kg
2.
Convert 2.5kg into pound (lbs)
Step 1. Det. The unit
to be replace
Kg to lbs
Step 2. Determine
the given = 2.5 kg
Step 3. Det the conversion factor 1kg = 2.2lbs therefore
CF = 2.2lbs/1kg
Step 3 Multiply
2.5kg x 2.2lbs/1kg (kg will be cancelled)
= 5.5lbs
3. 8.0 x
106 cm3 to m3
cm3 to m3
Given: 8.0 x 106 cm3
1m =
100cm ; 1 m3
= 1000000 cm3 CF =
1 m3 /1000000 cm3
m3
=
( 8.0 x 106 cm3 )
x 1 m3 /1000000 cm3 cm3
will be cancelled
= 8.0 m3
4. Convert 7.4 m3 to L
Given: 7.4 m3
1L = 0.001 m3 CF
= 1L/0.001 m3
7.4 m3 x 1L/0.001 m3 = 7400L
5. Convert 1g/ cm3 to kg/ m3
Det. The conversion factors, in this case we will have two conversion
factor
1000g = 1kg
and 1 m3 = 1000000 cm3
6. kg/ m3 = 1g/ cm3 x
1kg/1000g x 1000000 cm3 / 1 m3
g and cm3 will be cancelled
= 1000 kg/ m3
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