1.2 base derived quantities

Chapter 1
Introduction To Physics

1.2 Base & Derived Quantities

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Learning Outcomes


PHYSICAL QUANTITY
Hehehe….
Can u guess Wow! Is this
what is my real??!
height?

Weight Mass Time

PHYSICAL QUANTITY
The quantity that can be measured
Measurable :
The process of determining the
value of a quantity using a scientific
instrument with a standard scale
Example:
Mass, weight, height, time,
temperature www.myfunphysicsworld.blogspot.com

Length of meter ruler = 100.0 cm
Which is
1. Physical quantity?
2. Numerical value?
3. Unit of measurement?


Non-physical Quantity

The quantity that cannot be
measured.
Example:
Feelings-happy , sad ,
angry ….

Physical Quantities

Base Quantities Derived Quantities


Base Quantity Derived Quantity
Physical quantities Physical quantities
that cannot be derived from base
defined in terms of quantities by
other physical multiplication or
quantities division or both
Length, Mass, Density, Pressure,
Time, Force….
Temperature,
Electric Current

Base Quantities
Physical quantities that cannot be defined
in terms of other physical quantities.
Unit : base unit
Name & Symbol S.I. Unit & Symbol
Length / l meter / m
Mass / m kilogram / kg
Time / t second / s
Temperature / T kelvin / K
Electric Current / I ampere / A

Derived Quantities
Physical quantities derived from base
quantity (multiplication or division or both)
Unit : Derived Unit
Name & Symbol S.I. Unit & Symbol
Velocity / v meter per second / ms-1
Force / F Newton / N
Pressure / P Pascal / Pa
Weight / W Newton / N
Density / ρ kg m-3

DERIVED QUANTITIES


(a) Show the relationship between
the following derived quantities and
their corresponding base quantities.

(b) Derive the units for the following
physical quantities

Density = mass / volume
= mass / (length)3
= kg m-3

Prefix Symbol Value
Tera T 1012
Giga G 109
Mega M 106
Kilo k 103
Hecto h 102
Deca da 101
Deci d 10-1
Centi cm 10-2
Milli m 10-3
Micro ų 10-6
Nano n 10-9
pico p 10-12

4amanah 10jan until here
Ask them to memorise prefixes follow text
book
Ask to collect rm1 by next week
30 students


Changing Unit


Prefix Value
10 (A) -(B)
Tera / T 1012
A = initial prefix Giga / G 109
B = final prefix Mega / M 106
Kilo / k 103
1.23 ųm = _____ km Hecto / h 102
Deca /da 101
10-6-(3) =10-9 Deci / d 10-1
Centi/cm 10-2
1.23 ųm
Milli / m 10-3
= 1.23 x 10-6-(3) km Micro / ų 10-6
Nano / n 10-9
= 1.23 x 10-9 km
Pico / p 10-12

Prefix Value
Tera / T 1012 4.56 Mg = _____ ng
Giga / G 109
Mega / M 106
Kilo / k 103 106-(-9)= 1015
Hecto / h 102
Deca /da 101 4.56 Mg
Deci / d 10-1
Centi/cm 10-2 = 4.56 x 106-(-9)
Milli / m 10-3 = 4.56 x 1015 ng
Micro / ų 10-6
Nano / n 10-9
Pico / p 10-12 www.myfunphysicsworld.blogspot.com

Change to S.I. Unit
456 g/cm3
=456 x 10-3 x 106 kg m-3
= 456 g
= 456 x 103 kg m-3
cm3
= 4.56 x 105 kg m-3
= 456 x 10-3 kg
1 x (10-2 m)3
= 456 x 10-3 kg
1 x 10-6 m3


Exercise 1

January 2011


1 For the following physical quantities,
derive their
i) base quantities
ii) units
(a) Velocity
(b) Acceleration
(c) Force
(d) Work
(e) Density

Derived Base Quantities Units
Quantities
a)Velocity displacement/time m/s
= length/time
b) Acceleration

c) Force

d) Work
e) Density

(a) Velocity

= displacement/time
= length/time
= m/s
=ms -1


(b) Acceleration
= Change in Velocity
time
= length
(time)2
= m/s2
= m s-2

(c) Force
= mass x acceleration
= mass x length
(time)2
= kg m s-2
= Newton
=N

(d) Work
= Force x Displacement
= mass x acceleration x length
= mass x length x length
(time)2
=
kg m2 s-2
= Nm = J

e) Density
= mass
volume
= mass
(length)3
= kg m-3


Derived Base Quantities Units
Quantities
a)Velocity displacement/time m/s
= length/time
b) Acceleration Change in m/s-2
Velocity/time
= length/(time)2
c) Force Mass x acceleration
= (mass)(length)
(time)2
d) Work Force x
displacement
=

2 Show the relationship between
the following derived
quantities and their
corresponding base
quantities.

(a) acceleration
(b) momentum


3


1.2 base derived quantities

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