This document explains the concepts of motion, including different types such as linear, rotary, and reciprocating motion, alongside the distinction between distance and displacement. It emphasizes the differences between scalar and vector quantities, specifically speed and velocity, and introduces the concept of acceleration as the rate of change of velocity. Additionally, it discusses the effects of friction and gravitational forces on motion.

3. An object's momentum is directly
related to the object's mass and
velocity, and the total
momentum of all objects
in an isolated system (one not
affected by external forces) does not change
with time, as described by the law of
conservation of momentum.

4. As there is no absolute frame of
reference, absolute motion cannot be
determined. Thus, everything in the universe
can be considered to be moving.
More generally, motion is a concept that
applies to objects, bodies, and matter
particles, to radiation, radiation fields and
radiation particles, and to space, its
curvature and space-time. One also speak of
motion of shapes and boundaries.

5. Thus, the term motion in general
signifies a continuous change in the
configuration of a physical system. For
example, one can talk about motion of a
wave or about motion of a quantum
particle, where the configuration consists
of probabilities of occupying specific
positions.

7. Linear motion is the most basic
of all motions. Linear motion is the
type of motion in which all parts of
an object move in the same direction
and each part moves an equal
distance. Linear motion is measured
by speed and direction. Distance
travelled by an object per unit of
time is called velocity. Example: a
moving car.

8. Rotary motion is motion in
a circle.
This type of motion is the
starting point of many
mechanisms. Example: a
spinning wheel.
Reciprocating motion is
back and forth motion.
Example: the up and down
motion of a yo-yo.

9. Irregular motion is motion which has no
obvious pattern to its movement. Example: a
flying bee.
Uniform motion is motion at a constant
speed in a straight line. Example: a rolling
ball.
Very often, objects move by complicated
motion. Complicated motion can be broken
down into simpler types of motion. An
example of complicated motion is a flying
Frisbee. The movement of a Frisbee consists of
a linear motion and a rotary motion.

10. Frictional and gravitational forces affect the motion of objects.
Gravitational and frictional forces slow down the motion. The
frictional force which slows a body in motion is called kinetic
friction. When two objects slide past one another, for example,
when you push a box across the floor, part of the energy of your
pushing moves the box, and part of the energy is lost to kinetic
friction. The less textured the surface, the farther the object will
move. That happens because smooth surfaces have less frictional
force. Friction is affected by the texture of both the surface and
the moving object.

11. are two
quantities that may seem to mean the same thing yet
have distinctly different definitions and meanings.
Distance is a scalar quantity that refers to "how
much ground an object has covered" during its
motion.
Displacement is a vector quantity that refers to "how
far out of place an object is"; it is the object's
overall change in position.
To test your understanding of this distinction,
consider the motion depicted in the diagram below. A
physics teacher walks 4 meters East, 2 meters
South, 4 meters West, and finally 2 meters North.

12. Just as distance and displacement have distinctly
different meanings (despite their similarities), so
do speed and velocity. Speed is a scalar
quantity that refers to "how fast an object is
moving." Speed can be thought of as the rate at
which an object covers distance. A fast-moving
object has a high speed and covers a relatively
large distance in a short amount of time. Contrast
this to a slow-moving object that has a low speed;
it covers a relatively small amount of distance in
the same amount of time. An object with no
movement at all has a zero speed.

13. Velocity is a vector quantity that refers to
"the rate at which an object changes its
position." Imagine a person moving rapidly -
one step forward and one step back - always
returning to the original starting position.
While this might result in a frenzy of
activity, it would result in a zero velocity.
Because the person always returns to the
original position, the motion would never
result in a change in position.

14. Since velocity is defined as the rate at which
the position changes, this motion results in zero
velocity. If a person in motion wishes to
maximize their velocity, then that person must
make every effort to maximize the amount that
they are displaced from their original position.
Every step must go into moving that person
further from where he or she started. For
certain, the person should never change
directions and begin to return to the starting
position

15. Velocity is a vector quantity. As such, velocity
is direction aware. When evaluating the velocity of an
object, one must keep track of direction. It would not
be enough to say that an object has a velocity of 55
mi/hr. One must include direction information in
order to fully describe the velocity of the object. For
instance, you must describe an object's velocity as
being 55 mi/hr, east. This is one of the essential
differences between speed and velocity. Speed is a
scalar quantity and does not keep track of direction;
velocity is a vector quantity and is direction aware.

16. The average speed during the course
of a motion is often computed using
the following formula:
In contrast, the average velocity
is often computed using this formula.

17. Acceleration, in physics, is the rate of change
of velocity of an object. An object's acceleration is
the net result of any and all forces acting on the
object, as described by Newton's Second
Law. The SI unit for acceleration is the meter per
second squared(m/s2). Accelerations
are vector quantities (they
have magnitude and direction) and add according to
the parallelogram law. As a vector, the calculated
net force is equal to the product of the object's
mass (a scalar quantity) and the acceleration.

18. For example, when a car starts from a
standstill (zero relative velocity) and travels
in a straight line at increasing speeds, it is
accelerating in the direction of travel. If the
car turns there is an acceleration toward the
new direction. For this example, we can call
the accelerating of the car forward a "linear
acceleration", which passengers in the car
might experience as force pushing them back
into their seats. When changing directions,
we might call this "non-linear acceleration",
which passengers might experience as a
sideways force.

19. If the speed of the car decreases, this is
an acceleration in the opposite direction of
the direction of the vehicle, sometimes
called deceleration. Passengers may
experience deceleration as a force lifting
them away from their seats.
Mathematically, there is no separate
formula for deceleration, as both are
changes in velocity. Each of these
accelerations (linear, non-linear,
deceleration) might be felt by passengers
until their velocity and direction match that
of the car.

20. An object's average acceleration
over a period of time is its change
in velocity divided by the duration
of the period . Mathematically,