Gen.Physics1_Measurements 123456789101112

General Physics

1. “Quality is our mandate”
FIRST SEMESTER
QUARTER 1

2. “Quality is our mandate”
QUARTER 1: General Physics 1
OBJECTIVES:
1.Identify experimental errors and how to
estimate errors from multiple
measurements of a physical quantity using
variance;
2.Solve measurement problems involving
conversion of units and expression of
measurements in scientific notation;

3. “Quality is our mandate”
QUARTER 1: General Physics 1
OBJECTIVES:
3. Demonstrate how to add vectors
graphically and by component
method
4. Explain the importance of
measurements in daily life

4. Measurements

5. Units of Measurement : SI Unit
Système International (SI) d’Unités
International agreement on the metric units
for use in science (1960)

6. Units of Measurement : Prefixes
Prefixes : They are used to indicate decimal
fractions or multiples of various units.

7. Unit Conversionunit desired
unitgiven
unit desired
unit given 
Conversion factor
Example: The speed of N
2in air at 25
o
C is
515 m/s. Convert the speed into mile/hour

8. Length and Mass
Length :1 meter (m) = 100 cm
Mass :1 kilogram (kg) = 1000 g
Metric to Englishconversion
1 m = 1.093613 yard
1 cm = 0.393701 inch
1 kg = 2.204623 lb
NOTE: Mass and weight are not the same thing. Mass is an intrinsic
property of matter, but weight depends on the gravity.

9. Temperature
Water freezing Water boiling
Celsius scale (
o
C) 0 100
Fahrenheit scale (
o
F) 32 212
Kelvin : K =
o
C + 273.15 (exact)
Absolute zerotemperature : 0 K = 273.15
o
C
The lowest attainable temperature in our universe
o
C = 5/9 (
o
F 32)
o
F = 9/5(
o
C) + 32

10. Temperature
(98.6
o
F32)5/9 = 37
o
C
37
o
C + 273.15 = 310.15 K
William Thomson Kelvin
(1824-1907)

11. Significant Figures
•Scientist use significant figures to
determine how precise a
measurement is
•Significant digits in a measurement
include all of the known digits plus
one estimated digit

12. Rules for Significant figures
Rule #1
•All non zero digits are ALWAYS
significant
•How many significant digits are in the
following numbers?
•274
•25.632
•8.987
•3 Significant Figures
•5 Significant Digits
•4 Significant Figures

13. Rule #2
•All zeros between significant digits are
ALWAYSsignificant
•How many significant digits are in the
following numbers?
504
60002
9.077
3 Significant Figures
5 Significant Digits
4 Significant Figures

14. Rule #3
•All FINALzeros to the right of the
decimal AREsignificant
•How many significant digits are in the
following numbers?
32.0
19.000
105.0020
3 Significant Figures
5 Significant Digits
7 Significant Figures

15. Rule #4
•All zeros that act as place holders are
NOTsignificant
•Another way to say this is: zeros are
only significant if they are between
significant digits OR are the very final
thing at the end of a decimal

16. How many significant digits are in the
following numbers?
0.0002
6.02 x 10
23
100.000
150000
800
1 Significant Digit
3 Significant Digits
6 Significant Digits
2 Significant Digits
1 Significant Digit

17. Rule #5
•All counting numbers and constants
have an infinite number of significant
digits
•For example:
1 hour = 60 minutes
12 inches = 1 foot
24 hours = 1 day

18. How many significant digits are in the
following numbers?
0.0073
100.020
2500
7.90 x 10
-3
670.0
0.00001
18.84
2 Significant Digits
6 Significant Digits
2 Significant Digits
3 Significant Digits
4 Significant Digits
1 Significant Digit
4 Significant Digits

19. Let’s try these examples…
200.99 (want 3 SF)
18.22 (want 2 SF)
135.50 (want 3 SF)
0.00299 (want 1 SF)
98.59 (want 2 SF)
201
18
136
0.003
99

20. Scientific Notation
•Scientific notation is used to express
very large or very small numbers
•I consists of a number between 1 &
10 followed by x 10 to an exponent
•The exponent can be determined by
the number of decimal places you
have to move to get only 1 number in
front of the decimal

21. Scientific Notation Examples
99.343
4000.1
0.000375
0.0234
94577.1
9.9343 x 10
1
4.0001 x 10
3
3.75 x 10
-4
2.34 x 10
-2
9.45771 x 10
4
Place the following numbers in scientific
notation:

22. Going from Scientific Notation to
Ordinary Notation
•You start with the number and move
the decimal the same number of
spaces as the exponent.
•If the exponent is positive, the number
will be greater than 1
•If the exponent is negative, the number
will be less than 1

23. Going to Ordinary Notation Examples
3 x 10
6
6.26x 10
9
5 x 10
-4
8.45 x 10
-7
2.25 x 10
3
3000000
6260000000
0.0005
0.000000845
2250
Place the following numbers in ordinary notation:

24. •Significant Figures in Calculations
Addition & Subtraction: The number of
decimal places in the answer should be
equal to the number of decimal places in
the value with the fewest decimal
places.
Example: 12.0035 g
3.72 g
0.015 g
15.74 g
(4 decimal places)
(2 decimal places)
(3 decimal places)
(2 decimal places)

25. •Significant Figures in Calculations
Multiplication & Division: The number
of significant figures in the answer
should be the same as the value with
the fewest significant figures.
Example:
12.36 mL x 1.7 g = 21 gmL
4 sig. fig.
2 sig. fig.
2 sig. fig.
Note: Definitions and counted numbers have an unlimited number
of significant figures.

26. Accuracy –a statement of how close
a measured value is to the true or
accepted value.
Precision –a statement of how
reproducible the measured results are
FIGURE 1 FIGURE 2
ACCURATE PRECISE