Physics 101

Physics 10 Coverage•Kinematics•Newton’s Laws of Motion•Uniform Circular Motion and Universal Law of

Gravitation

•Textbook: Halliday, et al. Principles of Physics 10th edition (International student version)

• URL: •Users of 9th ed, in order to access 10th ed. on-

line services, pls. submit your names to your teacher

•Vision :

•Mission:

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Computation of Grades

•Quiz 1 PS 1•Quiz 2 PS 2•Quiz 3 PS 3•Quiz 4 PS 4 Final Exam ____

______ ____ Recitation ____

Eleven (11) Weeks• Week Date Activity Week Date Activity • 1 7

• 2 8

• 3 9

• 4 10

• 5 11

• 6

Week 1

•Measurements (Exact and Inexact)•Rules of Significant Figures•Rules of Rounding Off and Scientific

Notation•Conversion of Units

Language of Measurements

•Physics is an experimental science. Experiments require measurements, and we generally use numbers to describe the results of measurements.

1.7

International System of Units (SI)

Measurement• In science, we have the seven physical

standards:

Unit Prefixes

The British System

•British units are now officially defined in terms of SI units, as follows:

Length: 1 inch = 2.54 cmForce: 1 pound(force) = 4.448221615260 newtons

Dimensional Analysis/Unit Consistency•An equation must always be dimensionally

consistent.

• Mass = M• Length = L• Time = T

Some examples:• Density has the quantity of M / L3

• Speed has the quantity of L / T (i.e. miles per hour)

• Acceleration has the quantity of L /T2 • Force has the quantity of M L / T2

Question:

Can the left hand side of an expression A = B have different units than the right hand side?

Dimensional Analysis

•Checking equations with dimensional analysis:

x f xi vit 1

2at 2

Note: • Each term must have same dimension• Two variables can not be added if dimensions are

different• Multiplying variables is always fine• Numbers (e.g. 1/2 or p) are dimensionless

Check the equation for dimensional consistency:

2

2

2

)/(1mc

cv

mcmgh

Here, m is a mass, g is an acceleration, c is a velocity, h is a length

•Consider the equation:

•Where m and M are masses, r is a radius andv is a velocity.

•What are the dimensions of G ?

mv2

rG

Mm

r2

Conversion of Units1 inch = 2.54 cm 1 inch / 2.54 cm

= 1 1 m = 3.28 ft 1 m / 3.28 ft = 1 1 mile = 5280 ft 5280 ft / 1 mile

= 1 1 hr = 60 min = 3600 s 1 hr / 3600 s =

1

Example: Convert miles per hour to meters per second:

111hr

mi 1

hr

mi1

s

m

2

1

s

m447.0

s 3600

hr 1

ft28.3

m 1

mi

ft 5280

hr

mi 1

hr

mi1

Practice Exercise1. A platinum metal with density of 21.50 g/cu. cm

has a volume of 4.49 cu. cm. What is the mass in pound mass if 1 kg = 1000 g = 2.2 pound mass?

2. During your travel, you rent a small car which consumes 6 liters of gasoline per 100 km. a. What is the MPG (mi/gal) of the car ?•B. How gal of gasoline is needed to travel 1.25mi (There are 3.8 liters per gallon; 1.6 km in 1 mi)

Convert 172.9 0F to degrees Celsius.

Convert 172.9 0F to degrees Celsius.

0F = x 0C + 3295

0F – 32 = x 0C95

x (0F – 32) = 0C95

0C = x (0F – 32)95

0C = x (172.9 – 32) = 78.2895

1.7