PHYSICS –PHY101 VU
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Summary of Lecture 1 – INTRODUCTION TO PHYSICS
1. Physics is a science. Science works according to the scientific method. The scientific
method accepts only reason, logic, and experimental evidence to tell between what is
scientifically correct and what is not. Scientists do not simply believe – they test, and
keep testing until satisfied. Just because some “big scientist” says something is right, that
thing does not become a fact of science. Unless a discovery is repeatedly established in
different laboratories at different times by different people, or the same theoretical result
is derived by clear use of established rules, we do not accept it as a scientific discovery.
The real strength of science lies in the fact that it continually keeps challenging itself.
2. It is thought that the laws of physics do not change from place to place. This is why
experiments carried out in different countries by different scientists – of any religion or
race – have always led to the same results if the experiments have been done honestly and
correctly. We also think that the laws of physics today are the same as they were in the
past. Evidence, contained in the light that left distant stars billions of years ago, strongly
indicates that the laws operating at that time were no different than those today. The
spectra of different elements then and now are impossible to tell apart, even though
physicists have looked very carefully.
3. This course will cover the following broad categories:
a) Classical Mechanics, which deals with the motion of bodies under the action of
forces. This is often called Newtonian mechanics as well.
b) Electromagnetism, whose objective is to study how charges behave under the
influence of electric and magnetic fields as well as understand how charges can
create these fields.
c) Thermal Physics, in which one studies the nature of heat and the changes that the
addition of heat brings about in matter.
d) Quantum Mechanics, which primarily deals with the physics of small objects such
as atoms, nuclei, quarks, etc. However, Quantum Mechanics will be treated only
briefly for lack of time.
4. Every physical quantity can be expressed in terms of three fundamental dimensions:
Mass (M), Length (L), Time (T). Some examples:
1
2
2
22
12
Speed
Acceleration
Force
Energy
Pressure
LT
LT
MLT
M
LT
M
LT
−
−
−
−
−
−
You cannot add quantities that have different dimensions. So force can be added
to force, but force can never be added to energy, etc. A formula is definitely
wrong if the dimensions on the left and right sides of the equal sign are different.
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