Lect1 Introductory Physics

8/13/2019 Lect1 Introductory Physics

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SFZ3001/FZK3001

INTRODUCTORY PHYSICS


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Course outline

This course is intended to give a solid introduction to basic principles of

classical mechanics, waves and thermodynamics, to develop problem

solving skills, and to prepare university students for professional careers in

science

Classes : Sunday 8.00am9.00am (MK8)

Monday 9.00am11.00 am (MK11)

Time commitment

3hrs/week (class) Studying 5-6 hrs/week

Homework 5-6 hrs/week

A part from 8 hrs/day of your study time.

Assessment : Quiz/Task 20%

1sttest 15%

2ndtest 15% Tutorial 10%

Final exam 40%

100%


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Outline of course

1. Mechanics Physics & Measurement

Vector Algebra

Motion in one & two dimension

Forces: Newtons law of motion

Additional Forces Model & Circular Motion

Work & Kinetics Energy

Impulse & Linear Momentum

Rotation

Oscillations


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Continue

2. State of Matter Deformation of matter

Density & Pressure

Fluid Static & Dynamics

3. Sound

4. Temperature, Heat & The Equation of State

5. Electricity

6. Magnetism7. Modern Physics


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To see forward, first look backward

The earliest step toward science arose out of the

recognition of patterns of irregularity, which is i.e.the

sequence of day& night, the seasons & regular motion of

the heavenly bodiesraises question about their

causes.

The give & take between experimental observation, the

math. Formulation of descriptive & predictive theories, &

further experimental test of predictions of these theories

form the scientific method.

Physics underwent a series of revolutionary between1900 to 1925 which is sometime divided into classical

(pre-1900) and modern physics (post-1900).


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Another way to think physics is in term of scale. Newtons law of motion were thought for a long time to

be universally applicable. In the late 19thcentury, there

are scales at which these law should be replace

quantum mechanics to describe the behavior of matter atatomic scale & below, & other theories.

In the context of Newtons law, it includes the great

subject of classical physics- mechanics, waves,

thermodynamics, electricity & magnetism


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Physics & Measurement Many concept of physics most compactly express in the language of

mathematics.

Term as position, force, work and energy.

Basic SI (Systme Internationale) units

Length (1 meter)

(1889) - distance between 2 scratches on a bar of platinum-iridiumstored in International Bureau of Weight and Measures in Sevres,

France.

(1960)the wavelength of a particular orange-red light emitted by a

isotope of krypton gas (86Kr).

(1983)based on speed of light in vacumm, c. is the distance traveledby light ia a vacumm during the time interval of 1/299,792,458 s.

Property Name Abbreviation

Length Meter m

Mass Kilogram Kg

Time second s


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Time

- Defined as 1/86,400 of the mean solar day.

- (1967) Duration of 9,192,631,770 periods of particular vibration ofa cesium atom isotope (133Ce).

Mass

- Defined as the mass of one liter of water under certain condition oftemperature and pressure.

- (1901) KgThe mass of particular cylinder of platinum-iridium.

Other system of units

Cgs : based on centimetre,gram & secondderived directly from SI.

exp.: density of water=1g/cm3in cgs 103kg/m3in SI

British Engineering Sys. : based on inch, pound and second.

still use in USA in engineering application.


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Unit prefixes

- Prefixes in SI replace given powers of 10.


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Units & Unit conversion

Derived units with combination of the fundamental unit.

EnergyJoule (J) kg.m2/s2

ForceNewton (N) kg.m/s2

PressurePascal (Pa) kg/m.s2

Frequencyhertz (Hz) s

-1

. Conversion unit of different system

1 inch = 2.54 cm

Exp. : 15 in. = ? Cm

15 in. = 15 x 2.54 cm = 38 cm.


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Dimensional analysis

Three primary dimensionslength, time & mass

Abbreviation - [L],[T] and [M].

The dimension of a physical quantity is a algebraic

combination of it.

Speed, v, the dimension of it :

[v] = [L/T], or [v] = [LT-1] which is ms-1

Exp. : area = [L].[L] = [L2] = m2

The dimension on one side od an equation must be thesame as those on the other side.


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Scalar & vectors

Scalarhas no direction associated with it.mass, temperature etc.

A direction is needed for a complete description of

physical quantities.

Exp. Velocity of the ball requires specifying not only thespeed but also the direction of traveling.

Vectorsdescribe both magnitude/direction and a

direction.

It describe displacement, velocity, acceleration, force,electric field etc.


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Displacement

Displacement different

between 2 position of an

object.

From A to B, the vector is

K. With the magnitude of 3

kilometer and direction to

the northeast.

A

B

K


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Addition & Subtraction of Vectors

The result of successive

displacement is also adisplacement

C = A + B

The sum of the two vectorsknown as resultant vector.

Scalar multiplication, dD,means length of D have dmltply. of the vector D

Any vector D is written D = D,D is magnitude is unit vectorthat point in the direction of D

and has a magnitude of 1. In other word, the unit vector

simply specifies a direction.

A

B

C

D2D


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Component

The component vector of V

are the vector Vx and Vy.

V = V2x+V2

y.

from Pythagoras theorem

tan = V2x

V2y

Or tan-1(Vy/ Vx)

Equivalently

Vx= V cos Vy= V sin

If adding 2 vectors V and W,

V+W = (Vx+ Wx) + (Vy+ Wy) .

V

Vx

Vy


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Vectors in 3-dimensional space

3 unit vectors for 3 axesdenoted by , &k

Vector in 2 or 3D can be

specified with Cartesianset of axes (x,y,z)


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Example

1. Describe D in terms of

position vectors A and Bof the points A (2,3) and

B (5,4) (in cm).

2. Calculate length of D

and the angle it makeswith the x-axis.

A

B

A

D

B

0


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Ans.

1. A + D = B then D = BA

2. A=2 + 3 and B = 5 + 4

D = BA = (5-2) + (4-3) = 3 + 1

D = D2x+D2

y. = 32+ 12 = 3.2 cm

tan = Dx/ Dy= 1 cm / 3 cm = 0.33

then = 18o.

Lect1 Introductory Physics

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