chapter 1 measurement_mzmy.ppt

8/10/2019 Chapter 1 Measurement_mzmy.ppt

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PHY 130 : FUNDAMENTAL PHYSICS

COURSE WORKTest-20 %

Quiz & Assignment-10 %Experiment-20 %

FINALFinal exam - 50 %

TOTAL = 100 %


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SYSTEM OF UNITSCHAPTER 1


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SYSTEM OF UNITS

Basic Quantities

Derived Quantities

Units

Prefixes

Dimensional Analysis


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PhysicalQuantities

* Basis of physical

quantities * Combination of

one or more basic

quantity quantities

BASIC

QUANTITIES

DERIVED

QUANTITIES

Basis of physical quantitiesExample :

Length (m)Mass (kg)

Time (s)Temperature (K)Electric current (A)

Combination of one or more

basic quantities.

Example :Area (m2)

Volume (m3)

Velocity (ms-1)

Acceleration (ms-2)


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BASIC

QUANTITIES

COMBINATION OF

QUANTITIES

DERIVED

QUANTITIES

Length (Length)2

Area(m2

)

Length (Length)3 Volume(m3)

Length, time Length/time Speed(ms-1)

Length, time Length/(time)2 Acceleration(ms-2)

Length, mass Mass/(length)3 Density(kgm-3)

Mass, time (Mass x length)/(time)2 Force(kgms-2)


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SCIENTIFIC NOTATION

A way of writing numbers that accommodates values too largeor small to be conveniently written in standard decimal notation

In scientific notation, numbers are written in the form:

Example:

An electron'smass is about

0.000 000 000 000 000 000 000 000 000 000 910 938 22 kg.

In scientific notation, this is written 9.10938221031kg.
http://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Electron


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Used to simplify big numbers.

Replace powers of ten.

POWER PREFIX ABBREV.

x 10-12 pico p

x 10-9 nano n

x 10-6 micro

x 10-3 milli m

x 10-2 centi c

x 103 kilo k

x 106 Mega M

x 109 Giga G

x 1012 Tera T

PREFIXES


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3 km = ? m

1 km = 1000 m

3 km = 3 x 1000 m=3000 m

or 3 km = 3 km x 1000 m

1 km= 3000 m

CONVERSION OF UNITS


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45 cm = ? km

km4.5x10cm45

km45x10cm45

m1000

1km

cm100

1mxcm45cm45

4

5

CONVERSION OF UNITS


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35 km.hr-1= ? m.s-1

11ms9.72km.hr35

s

m

60x60

35x1000

1hr

km35

s60

1min

min60

1hr

km1

m1000

1hr

km35

hr1

km35

CONVERSION OF UNITS


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20 kg.m-3= ? g.cm-3

323

33

3

3

33

3

33

cm.g10x2m.kg20

cm

g

100x100x100

1000x20

m1

kg20

cm100

m1

kg1

g1000

m1

kg20

m1

kg20

cm100

m1

kg1

g1000

m1

kg20

m1

kg20

CONVERSION OF UNITS


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Three basic ways to describe a physicalquantity the space it takes, the matter itcontains, and how long it persists.

All measurements reduce tolength, time, and

mass Three primary dimensions: Length(L),

Mass(M), and Time(T)

Additional dimensions: electric current(A) andTemperature().

DIMENSIONS


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Dimensions of a quantity are the base units that

make it up; they are generally written using square

brackets.

Example: Speed = distance / time

Dimensions of speed: [L/T]

Quantities that are being added or subtracted

must have the same dimensions.

In addition, a quantity calculated as the solution

to a problem should have the correct dimensions.

DIMENSIONS DIMENSIONAL

ANALYSIS


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Check validity of equations/expressions Determine exponent of equations

Example 1 :

Given that an equation mass = density x area Is that

equation correct?

DIMENSIONAL ANALYSIS

A


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Answer :

If [left hand side] = [right hand side], then equation

is valid.

Therefore: [mass] = [density] x [area]

Density = mass / volumeVolume = length x width x height

Dimension density : [] = [M/ L3] = [ML-3]

Dimension area : [A] = [L2

] = [L2

]Dimension mass : [m] = [M]

[left hand side] = [right hand side]

[mass] = [density] x [area]

[M] = [ML-3] x [L2][M] = [ML-1]

Therefore, [left hand side] [right hand side].

The equation is not correct.


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ts as nm tkas

nmm

nmm

n

m

nm

TLL

TTLL

T

T

LL

tkas

2

2

2

][][

Example 2 :

Given that and and

Where k is constant. Find the values of m and n by using

the dimensional analysis.

Answer :


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If the equation is true, then the exponent of each

dimension on each side of the equation must be equal.

Hence, Looking at L;

Looking at T:

Solving for m and n ; m = 1 and n = 2

Therefore the equation s = kat2

The value of k is actually

This is an equation for an object accelerating from rest

i.e

nm2m01

TLTL

m1

nm20

2at2

1s


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chapter 1 measurement_mzmy.ppt

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