3. Kinematics
• Kinematics is the branch of classical
mechanics which describes the
motion of points, bodies (objects),
and systems of bodies (groups of
objects) without consideration of the
causes of motion.
• Kinematics as a field of study is
often referred to as the "geometry of
motion".
4. Motion
• a change in position of an object with
respect to a reference point and time
• Reference point/frame of reference –
starting point (origin) for measuring
motion
5. Rectilinear Motion
• another name for straight-line motion.
This type of motion describes the
movement of a particle or a body
• A body is said to experience
rectilinear motion if any two particles
of the body travel the same distance
along two parallel straight lines. The
figures below illustrate rectilinear
motion for a particle and body.
6. Natural and Violent Motions
• Aristotle classified motion into two
types:
1. Natural Motion – motion of an
object or a body to its natural place
Example:
A piece of stone will fall on the ground
when it is dropped from a certain
height
7. Natural and Violent Motions
2. Violent Motion – motion caused by
a force or the result of a push and
pull. When a force is not applied on
a body, it ceases to move.
8. Distance and Displacement
• Distance – length along a path
between two points
– total length travelled by an object or
person
Example: Peter walked from his house
50m East and walked back 20m West,
his total distance travelled is 70m.
50m + 20m = 70m
9. Distance and Displacement
• Displacement – refers to the shortest
distance between the object’s two
positions, like the distance between
its point of origin and its point of
destination, no matter what path it
took to get to that destination.
10. Scalar and Vector Quantities
• Scalar Quantities – completely
specified by magnitude alone. They
are described with a single number
(including units) indicating size,
magnitude or dimension. Other
common scalars are temperature,
mass, volume, time, speed and
distance.
11. Scalar and Vector Quantities
• Vector Quantities – physical
quantities that require both magnitude
and direction for their specification.
Because direction is an important
characteristic of vectors, arrows are
used to represent them.
14. Speed
• Speed is the distance that an object
travels per unit of time. To determine
speed, use the formula below:
speed = distance
time
Or in symbols: v = d
t
15. Speed
• The rate of motion or the speed of an
object is commonly expressed in
meters per second (m/s), centimeters
per second (cm/s) or kilometers per
hour (km/h)
16. Speed
• Example:
If a car travels 100 km in 2 h, its
speed is:
v = d
t
= 100 km
2 h
= 50 km/h
17. Speed
• In this case, 50 km/h represents the
car’s average speed or the total
distance travelled divided by the total
time to cover such distance.
18. Speed
• Example: (find distance)
How far will a car travel in 1.8 h
when its speed is 60 km/h?
v = d
t
d = vt
= (60 km/h)(1.8 h)
= 108 km
19. Seatwork #1
1. Hannah went running a distance of
120 m in 30 s. What was Hannah’s
rate of/ speed?
2. How far can a cyclist travel in 1.5
hours (h) if his average speed is 12
km/h?
20. Force
• Refers to the measurement of the
push or pull
• The SI unit for force is Newton (N)
21. Effects of Force on an object
• Change in shape
• Stop a moving object
• Speed up or slow down a moving
object
• Change in size
• Start a stationary object to move
• Change direction of motion
22. Types of Force
APPLIED FORCE
- is a force that is applied to an object
by a person of another object.
Example: a person is pushing a
desk
- the applied force is the force
exerted on the desk by the person
23. Types of Force
GRAVITY FORCE
- is the force with which the earth, the
moon or other massively large objects
attracts another object towards itself
- this is the weight of the object
24. Types of Force
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 to
support its weight
25. Types of Force
FRICTION FORCE
- is the force exerted by a surface as
an object moves across it or makes
an effort to move across it.
- Friction results from the two
surfaces being pressed together
closely, causing intermolecular
attractive forces between molecules
of different surfaces.
26. Types of Force
AIR RESISTANCE FORCE
- is a special type of 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.
27. Types of Force
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.
28. Types of Force
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.
29. VELOCITY
• Speed of an object in a particular direction
• An object at rest has zero velocity
• the table below shows the changing
velocity of a car from the time it started to
move until it has covered a distance of
500m
Total
Distance
0 100 200 300 400 500
Elapsed
Time
0 11 16 21 24 27
30. INSTANTANEOUS VELOCITY
• The velocity of a moving body at a
particular time is called instantaneous
velocity
change in distance
Instantaneous velocity = change in time
or
d
v = t
32. AVERAGE VELOCITY
• is the distance travelled in a particular direction
per unit time
• The average velocity of a moving body is
defined as the displacement divided by the
elapsed time:
displacement
Average velocity = elapsed time
d
v = t
33. AVERAGE VELOCITY
An airplanes takes off at 10 a.m. and
flies a straight path at 350 km/h until 1
p.m. Its velocity then changes to 400
km/h in the same direction until it
lands at 3:30 p.m. What is its average
velocity for the entire flight?
