introduction to physics for students
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Understanding Physics
Understanding Physics
1. Like all sciences, physics is based on experimental observations and quantitative measurements.
Understanding Physics
2. Historically, until nineteenth century, physics was called natural philosophy.
Understanding Physics
3. Physics is a branch of science concerning study of natural phenomena, that is, properties of matter and energy.
Understanding Physics
• 4. Some examples of natural phenomena are
(a) sunrise and sunset, (b) lightning and thunder, (c) rainbow and blue sky, (d) earthquake and tsunami.
Field of study in Physics
In general, physics is concerned with the study of energy and the properties and structure of matter.
Field of study in Physics
Physics
Classical Modern
Field of study in Physics
• deals with questions regarding motion and energyMechanics (forces and motion)HeatSoundEelectricity and magnetism Light
Physics
Classical Modern
Field of study in Physics
• concentrates on scientific beliefs about the basic structure of the material world
Physics
Classical Modern
Understanding Base Quantities and Derived Quantities
Base Quantities
• 1. Physical quantities are quantities that can be measured.
Base Quantities
2. A physical quantity can be represented by a symbol of the quantity, a numerical value for the magnitude of the quantity and the unit of measurement of the quantity.
Length, l = 1.67 ml - symbol 1.67is the value m - unit
Base Quantities
• 3. Base quantities are physical quantities that cannot be defined in terms of other quantities.
Base quantity :Length
Derived quantity :Area = length x length
Base Quantities
Base quantities SI base units
Name Symbol Name Symbol
Length l Metre m
Mass m Kilogram Kg
Time t Second s
Electric current
I Ampere A
Temperature T Kelvin K
Derived Quantities
1 Derived quantities are physical quantities derived from base quantities by multiplication or division or both. The unit for a derived quantity is known as a derived unit.
Derived Quantities
takenTime
ntDisplaceme
takenTime
velocityinChanges
ms -1
volume
Mass kg
m3
Derived quantities Derived units
Area = Length x breadth [Area] = m x m = m2
Velocity = [Velocity] = = ms–1
Acceleration=
Density = [Density] = = kgm–3
m
s
[Acceleration] = = ms–2
Vectors and Scalars
ScalarA SCALAR is ANY quantity in
physics that has MAGNITUDE, but NOT a direction associated with it.
Magnitude – A numerical value with units.
Scalar Example
Magnitude
Speed 20 m/s
Distance 10 m
Age 15 years
Heat 1000 calories
Temperature 37OCMass 100kg
Volume 5m3
VectorA VECTOR is ANY quantity in
physics that has BOTH MAGNITUDE and DIRECTION.
Vector Magnitude & Direction
Velocity 20 m/s, NAcceleration 10 m/s/s, EWeight 100N
(toward center of the earth)
Force 5 N, West
Fav,,
Vectors are typically illustrated by drawing an ARROW above the symbol. The arrow is used to convey direction and magnitude.