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PHYSICS
MEASUREMENTS
o Accurate measurements play an important
role in different vocation and profession.
SI FUNDAMENTAL UNITS
SI base units are the standard units of
measurement defined by the
International System of Units (SI) for the
seven base quantities of what is now
known as the International System of
Quantities: they are notably a basic set
from which all other SI units can be
derived.
THE SEVEN SI BASE UNITS
NAME BASE
QUANTITTY
SYMBOL
second time s
meter length m
kilogram mass kg
ampere electric current A
kelvin thermodynamic
temperature
K
mole amount of
substance
mol
candela luminous
intensity
cd
SCIENTIFIC NOTATION
UNIT CONVERSION
ACCURACY AND PRECISION
In measurement of a set, accuracy is
closeness of the measurements to a
specific value, while precision is the
closeness of the measurements to each
other.
SYSTEMATIC AND RANDOM
Random errors in experimental
measurements are caused by unknown
and unpredictable changes in the
experiment. These changes may occur
in the measuring instruments or in the
environmental conditions.
Systematic errors in experimental
observations usually come from the
measuring instruments. They may occur
because:
a) there is something wrong with the
instrument or its data handling system,
or
b) because the instrument is wrongly used
by the experimenter.
o The accuracy of a measurement is how
close the measurement is to the true value
of the quantity being measured. The
accuracy of measurements is often
reduced by systematic errors, which are
difficult to detect even for experienced
research workers.
SYSTEMATIC
ERROR
RANDOM
ERROR
Systematic error is the
one that deviates from
the true value of
measurement by a
fixed amount.
Random error is the
one that varies and
which is likely to be
positive or negative.
It remains constant or
changes in a regular
fashion in repeated
measurements of the
same quantity.
It is inconsistent and
does not repeat in the
same magnitude or
direction except by
chance.
Discovered
experimentally by
comparing a given
result with a
measurement of the
same quantity
performed using a
different method or by
using a more accurate
measureing
instrument.
Discovered by
performing
measurements of the
same quantity number
of the time under the
same conditions.
Caused by some flaw
in the experimental
apparatus or a flawed
experiemntal design.
Caused by
unpredictable
variations in the
readings of a
measurement device.
It can be eliminated
using proper
tachnique, calibrating
equipment, and
employing standards.
It can be reduced by
taking average of a
large number of
observations.
MEAN, STANDARD DEVIATION, AND
VARIANCE
VECTORS
Scalar Vectors
Magnitude Magnitude and
Direction
Distance
Speed
Mass
Temperature
Volume
Displacement
Velocity
Force
Acceleration
Resultant: a single vector that produces the
same effect as to two or more vectors
Vector Addition: associative and commutative
Speedometer: measure the instantaneous
speed of a car
Average Speed: the total distance of an
object over the time interval
Represents The Quantity Of
Displacement: 30 km, South
Represents The Quantity Of Speed: 5
m/s
Represents The Quantity Of Velocity: 29
km/h, 360 north of east
FREE-FALL AND PROJECTILE MOTION
FREE-FALL
An object is in free-fall when the only
force acting on the object is the force of
GRAVITY.
An object is in free-fall if is not touching
any other object.
There is no AIR RESISTANCE.
When an object is in free-fall (Earth) will
have a -9.81 m/s
g earth = 9.81 m/s2 (positive)
Acceleration Due to Gravity Comparison
Body Acceleration Due
to Gravity, "g" [m/s²]
Sun 274.
Mercury 3.
Venus 8.
Earth 9.
Moon 1.
Mars 3.
Jupiter 25.
Saturn 11.
Uranus 10.
Neptune 14.
Pluto 0.
PROJECTILE MOTION:
Projectile motion is an object upon
which the only force is gravity. Gravity
acts to influence the vertical motion of
the projectile, thus causing a vertical
acceleration. The horizontal motion of
the projectile is the result of the
tendency of any object in motion to
remain in motion at constant velocity.
Solving Projectile Motion:
Vertical Horizontal
Acceleration = -/+ 9.
m/s2 (constant)
Horizontal distance
(dh)
Vertical Distance
(dv/∆𝑥)
Initial velocity (Vi) Horizontal Velocity
(Vh) Final Velocity (Vf)
Time (t) Time (t)
To solve for vertical 3
variables are needed
To solve for horizontal
2 variables are
needed
Key points:
Range: the horizontal distance of the
projectile motion
The motion of a ball rising and then
falling in free fall:
I. The ball has constant acceleration as
it moves upward.
II. The ball has constant acceleration at
the top of its path.
III. The ball has constant acceleration as
it moves downward.
Vertical velocity is zero: The motion of the
projectile at its highest point
The x-component of the velocity of the ball
is the same throughout the ball's flight
FREE-BODY DIAGRAM AND NEWTON’S
FIRST LAW OF MOTION
UAM is
used to
find the
equation
of
Projectile
Motion.
Republic Act No. 8750: "Seat Belts Use Act of
1999." (August 5, 1999)
FORCE
A force is a push or pull acting upon an
object as a result of its interaction with
another object.
TYPES OF FORCE
Contact Forces Action-at-a-distance
Forces
Frictional Force
Tension Force
Normal Force
Air resistance
Force
Applied Force
Spring force
Gravitional Force
Electrical Force
Magnetic Force
TYPES OF FORCE
I. APPLIED FORCE ( Fapp ): An applied force
is a force that is applied to an object by a
person or another object.
Example: A person is pushing a book
II. GRAVITY FORCE (also known as Weight)
( Fgrav ): The force of gravity is the force
with which the earth, moon, or other
massively large object attracts another
object towards itself. By definition, this is
the weight of the object. All objects upon
earth experience a force of gravity that is
directed "downward" towards the center of
the earth.
o The force of gravity on earth is always
equal to the weight of the object as found
by the equation:
Fgrav = m * g
where g = 9.8 N/kg (on Earth)
and m = mass (in kg)
III. NORMAL FORCE ( Fnorm ): The normal
force is the support force exerted upon an
object that is in contact with another stable
object.
Example: a book is resting upon a
surface, then the surface is exerting an
upward force upon the book in order to
support the weight of the book.
IV. FRICTION FORCE ( Ffrict ): The friction
force is the force exerted by a surface as an
object moves across it or makes an effort to
move across it. There are at least two types
of friction force - sliding and static friction.
Example: a book slides across the
surface of a desk, then the desk exerts a
friction force in the opposite direction of its
motion.
o The maximum amount of friction force that
a surface can exert upon an object can be
calculated using the formula below:
Ffrict = μ • Fnorm
V. AIR RESISTANCE FORCE ( Fair ): The air
resistance is a special type of frictional
force that acts upon objects as they travel
through the air. The force of air resistance
is often observed to oppose the motion of
an object.
Example: It is most noticeable for objects
that travel at high speeds (e.g., a skydiver
or a downhill skier) or for objects with
large surface areas. Air resistance
VI. TENSION FORCE ( Ftens ): The tension
force is the force that is transmitted through
a string, rope, cable or wire when it is pulled
tight by forces acting from opposite ends.
Example: The tension force is directed
along the length of the wire and pulls
equally on the objects on the opposite
ends of the wire.
VII. SPRING FORCE ( Fspring ): The spring
force is the force exerted by a compressed
or stretched spring upon any object that is
attached to it. An object that compresses or
stretches a spring is always acted upon by
a force that restores the object to its rest or
equilibrium position.
o For most springs (specifically, for those
that are said to obey "Hooke's Law"), the
