Einstein developed the Special Theory of Relativity in 1905 to resolve conflicts between Maxwell's Electromagnetic Theory of Light and Newtonian Mechanics. The Special Theory of Relativity is based on two postulates: 1) the laws of physics are the same in all frames of reference moving at a constant velocity; and 2) the speed of light has the same constant value in all reference frames. Einstein showed that space and time are relative rather than absolute, resolving discrepancies between prevailing theories of light, electromagnetism, and motion.

1. SPECIAL THEORY OF
RELATIVITY

2. PRE-LESSON ACTIVITY
• A. Complete the Table of the Electromagnetic Spectrum of
Light.1. 2. 3. Green 4. 5. Violet
6. Microwaves 7. 8. 9 Gamma Rays
10−1 10−2 10−3 10−4
10−5
10−6
10−7 10−8 10−9 10−10 10−11
Visible Light
Red Orange Yellow Blue Indigo
Radiowav
es
Infrared Ultraviolet
rays
X-ray

3. B. Solve the following problems. Use the Formula of Newton’s Second
Law of Motion (F=ma), where: F – Force, m – mass and a –
acceleration.
1. Find the net force required to give an automobile of mass 1600g an
acceleration of 4.5 m/𝑠2
.
2. Give the mass of an object that is experiencing a net force of 200 N
and an acceleration of 500 m/𝑠2.
3. Find the acceleration of a car weighing 100 kg and has a force of
100 N.
4. What is the acceleration of a wagon with a mass of 20 kg if a
horizontal force of 64 N is applied to it?
5. An object accelerates 12.0 𝑚/𝑠2 when a force of 6.0 newtons is
applied to it. What is the mass of the object?

4. SPECIAL THEORY OF RELATIVITY
•Coined and developed by Albert Einstein
in 1905 as an answer to the long-debated
conflict between James Clerk Maxwell’s
Theory of Electromagnetism and Isaac
Newton’s three Laws of Motion.

5. THE THEORIES
•Long before the development of the special
theory of relativity, there were two great
theories of physics:
1.Theory of Electromagnetism
2.Three Laws of Motion

6. NEWTONIAN MECHANICS
• It is ground on the use of Newton’s three laws of motion.
• It explains that space (distance), time, and mass, are absolute
which means that the distance between two objects and the
time that passes between two events does not depend on the
environment where the object is in.
• According to the Newton’s second law, object in the
environment moves in a straight line; hence, the change of
location from one environment to another environment must
register a straight line to other straight lines.
• Moreover, it is said that no matter where you are or how fast
you are moving, there will be no changes in space time. In all
places, a kilometer is a kilometer and a minute is a minute. And

7. MAXWELL’S ELECTROMAGNETIC THEORY OF
LIGHT
• Maxwell had predicted that the electric field, magnetic field and
light are different representations of the same phenomena or
event.
• He predicted that visible lights are electromagnetic waves that
move in a manner like ripples in the water when a stone is
dropped.
• Light as wave have both electrical and magnetic components
and that it moves at a constant speed of 186,000 miles per
second. It means that the speed of light is the same for
everything and for all observers.

8. THE CONFLICT
•According to Maxwell, light in a vacuum moves
at 186,000 miles per second and does not
change for all observers and situation.
•According to Newtonian physics, all aspects
speeds are relative – meaning speed depend on
the observers, viewpoint and situation.

9. RESOLUTION: EINSTEIN AND THE SPECIAL
THEORY OF RELATIVITY
•In 1905, Einstein published his observation
about the differing ideas of the two theories
through special theory of relativity.
•He stressed that while Newtonian physics is
true and Maxwell theory is also correct.

10. TWO FOUNDATIONS OF SPECIAL THEORY
OF RELATIVITY
•1. Consistent Law Principle
•2. Constant Speed

11. •1. Consistent Law Principle
“ the laws of physics are the same in all frames
of reference that are moving at a constant
velocity with respect to one another.”
Example:
A teenage boy is standing inside a train that is passing equally
between two oaks trees. Because the train is moving, he saw that
a lightning struck the tree on his left first then on the tree on the
right. Another boy, who is standing at a train platform, also saw
the same. Only, in his viewpoint, the lightning struck both trees
at the same time.

12. •2. Constant Speed
“ the speed of light in an empty space has the
same magnitude for all observers regardless of
their velocity.”
Example:
An astronaut that is moving towards the source of light will
thank that light is moving at 186,000 miles per second. Hence,
an astronaut that is not moving towards the source of light will
think that light is moving at 186,000 miles per second. In short,
regardless of the rate movement of the source of light and the