1. General Physics (PHYS101)
Golibjon Berdiyorov

2. Syllabus and teaching strategy
Lecturer:
Golibjon Berdiyorov, Room 148 Physics Building
Phone: /2283
Office Hours:
Sunday-Thursday:
Lectures:
Sunday: pm-4.10pm (6/125)
Tuesday: 3.20pm-4.10pm (6/125) 25-27
Thursday: 3.20pm-4.10pm (6/125) 25-27
Recitation:
Monday: 1.10pm-2.00pm (6/209) 25
3.20pm-4.10pm (6/165) 26
4.20pm-5.10pm (6/201) 27

3. Assessment: Grading DN grade: 3 or more unexcused absences in the LAB
12 unexcused absences in lecture+recitation

4. Format for Active Learning
Warm up for lectures:
Read the text(use a highlighter, if you prefer)
Understanding physics (lectures):
Answer questions in class
Bring lecture notes, textbook…
Challenge yourself (homework):
Homework
Play with physics (lab):
Discover with hands-on experience
Practice, practice and practice!!!

5. Units, Changing units, Significant figures
Lecture 01
(Chap. 1, Sec. 1-3)
Units, Changing units, Significant figures

6. Measurements Physics is based on measurement of physical quantities
1 nanometre =1.0 × 10-9 m
1 light year =9.4×1015 m
Examples are: length, mass, time, electric current, magnetic field, temperature, pressure ...
All physical quantities have dimensions: dimensions are basic types of quantities that can be measured or computed.

7. Base dimensions These quantities are the basic dimensions: Length [L]
Mass [M]
Time [T]
Other physical quantities are defined in terms of these base quantities:
- [velocity] = [length]/[time] = [L]/[T]
- [volume]=[length]3=[L]3
- [density]=[mass]/[volume]=[M]/[L]3
- [force] = [mass][length] /[time]2 = [M][L]/[T]2

8. Units for physical quantities
A unit is a standard amount of a dimensional quantity.
Units can be chosen for convenience:
Science [L]:
1 angstrom =1.0 × 10-10 metres
1 light year = × 1015 metres
US customary [L]:
1 ft = m
1 mile = 1.6 km
12 inches in a foot, three feet in a yard
A single unified system of units makes life easier!

9. International System of Units
(metric system)
Basic SI Units
Length meter m
Time seconds s
Mass kilogram kg
Electrical current ampere A
Temperature Kelvin K
Luminous intensity candela cd
Amount of substance mole mol
These are the only units necessary to describe any quantity.

10. Si derived units Length [L] m Time [T] s Mass [M] kg
[Area] = m2 square meter
[Volume] = m3 cubic meter
[Density] = kg/m3 kilogram per cubic meter
[Speed] = m/s meter per second
[Acceleration] = m/s2 meter per second squared
[Force]: N (Newton) = kg m/s2
[Frequency]: Hz (Hertz) = s-1
[Pressure]: Pa (Pascal) = N/m2
[Energy]: J (Joule) = N m
[Power]: W (Watt) = J/s

11. Conversion of Units 10 m/s = 36 km/h
One can measure the same quantity in different units. For instance distance can be measured in miles, kilometres, meters etc. Velocity can be measured in km/hour, m/s etc.
If physical quantities are measured in different units, then they should be converted to the same units.
10 m/s = 36 km/h
vman-ground= 5km/h + 10 m/s = 15?? -No
vman-ground= 5 km/h + 36 km/h = 41 km/h

12. Conversion of Units: Chain-link method
Example 1: Express 3 min in seconds?
1= 60s 1 min = 1 min 60s
1min = 60 s
Conversion Factor?
3min=3min x 1=3min x 60 s 1 min =180 s
Example 2: How many centimeters are there in 5.30 inches?
1= 2.54 cm 1 in
1 in=2.54 cm
5.30 in=5.30 in x 1=5.30 in x 2.54 cm 1 in =13.5 cm

13. Conversion of Units Example 3: Express 200 km/h in miles/s?
1 km = 0.6 miles
1h = 60 min = 60 x 60 s = 3600 s
200 km/h= 200 x 0.6 miles/3600 s = 0.03 miles/s
Example 4: Express 200 km/h in m/s?
1 km = 1000 m
1 h = 3600 s
km/h --> m/s :3.6
m/s --> km/h x3.6
200 km/h= 200 x 1000 m/3600 s = m/s
Example 5: Express 16 m/s in km/h?
1 m = (1/1000) km
1 s = (1/3600) h
16 m/s= 16 x (1/1000) km/(1/3600) h = 16x3600/1000 km/h=57.6 km/h

14. Scientific notations 384000 km=3.84 x 105 km 0.0000013 m=1.3 x 10-6 m
Expanded form
1 x 100 1
1 x 101 10
1 x 102
100
1 x 103
1000
1 x 106
1 x 10-1
1/10 or 0.1
1 x 10-3
1/1000 or 0.001
1 x 10-6 km m
km=3.84 x 105 km
m=1.3 x 10-6 m
Can we write them in a compact form?
101 = 1.01 x 102
4321 = x 103
1.23 = 1.23 x 100
0.25 = 2.5 x 10-1
= x 10-4

15. Prefixes and Notation
The following prefixes indicate multiples of a unit.
Multiplier
Prefix
Symbol
1012
tera T
109
giga G
106
mega M
103
kilo k
10-3
milli m
10-6
micro μ
10-9
nano n
10-12
pico p
10-15
femto f

16. Rounding Speed of light: c=299 792 458 m/s c=2.99 792 458 x 108 m/s
Overestimation: digits 5 to 9 can be dropped from the decimal place during the rounding, however, one should be added to the digit in front of it.
Underestimation: the following digits can just be dropped from the decimal place: 0, 1, 2, 3, an 4.
Example 1. Round c to a nearest 1000th.
c=2.998 x 108 m/s.
Example 2. Round c to a nearest 10th.
c=3.0 x 108 m/s.
Example 3. Round to a nearest integer.
274
Example 4. Round to 2 significant figures.
270

17. Order of magnitude
An order of magnitude calculation is a rough estimate that is accurate to within a factor of about 10.
It is useful if you want to get a quick rough answer.
The order of magnitude of a quantity is the power of ten when quantity is expressed in scientific notation
A=7 600 = 7.6 x The order of magnitude of A is 3
B=3 700 = 3.7 x The order of magnitude of B is 3
A=7 600 ~ = The nearest order of magnitude of A is 4
B=3 700 ~ = The nearest order of magnitude of B is 3

18. Uncertainties in measurements
All measurements are subject to an uncertainty
These uncertainties can be due to e.g. limitations in the measuring tools or fluctuations in the measured quantities.
The accuracy of the measurements are determined by significant figures.

19. Rules for Significant Figures
1. All nonzero figures are significant
2. All zeros between nonzeros are significant
3. Zeros at the end are significant if there is a decimal
point before them
4. All other zeros are non-significant

20. Rules for Significant Figures
Not significant
zero at the beginning
Not significant
zero used only to locate the decimal point
Significant
all zeros between nonzero numbers
Significant
all nonzeros
integers
Significant
zeros at the end of
a number to the right
of the decimal point
Just take care of zeros

21. Operations with Significant Figures
When adding or subtracting, round the results to the smallest number of decimal places of any term in the sum

22. Operations with Significant Figures
When multiplying or dividing, round the result to the same accuracy as the least accurate measurements (i.e. the smallest number of the significant figures)
Example: Calculate the surface area of a plate with dimensions 4.5 cm by 7.32 cm.
A=4.5 cm x 7.32 cm=32.94 cm2.
A=33 cm2.

23. Summary
Dimensions are basic types of quantities that can be measured or computed.
Base dimensions are length, time, and mass.
A unit is a standard amount of a dimensional quantity.

24. Summary Scientific notations Order of magnitude: 10x (x=1,2,3 ..)
Rounding

25. Summary Significant figures Uncertainties in the measurements
It is important to control the number of digits or significant figures in the measurements.

26. Express speed of sound (330 m/s) in miles/h
(1 mile = 1609 m)
738 miles/h
730 miles/h
1 shake = 10-8 sec. Find out how many nano seconds (ns) are there in 1 shake (1ns=10-9s).
1 ns
10 ns
Express the following numbers in scientific notations:
a) b) c) 54800
a) 1.5 x b) 2 x c) 5.48 x 104