Motion

2. When you stand on the corner of a busy
street on a sunny day, you will see cars
moving at different rates. You will also feel
the heat coming from the sun on your skin
and the pull of gravity on your feet when you
walk from one place to another. These
simple activities are just few of the examples
of physics in everyday life.

3. This unit will allow you to appreciate the
applications of physics concepts in the world
you live in. You will explore topics on
mechanics to describe how objects around
you move. You will also be fascinated with
how the world functions with the help of the
properties of heat, light, and sound.

4. CHAPTER 6:
MOTION
DESCRIBING MOTION

5. MECHANICS
Mechanics is a field of physics which
deals with force and energy and their
interactions. It is a broad field which has
several branches. Two of these branches
are kinematics and dynamics.

6. KINEMATICS
Kinematics is a branch of mechanics that
studies the description of motion of
objects.

7. DYNAMICS
Dynamics is also a branch of mechanics
concerned with forces that cause motions
of objects.

8. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Describe the motion of an object in
terms of distance or displacement,
speed or velocity, and acceleration;

9. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Differentiate quantities (in terms of
magnitude and direction) using the
concepts of distance versus
displacement, and speed versus velocity;

10. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Compare and contrast distance and
displacement;

11. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Compare and contrast speed and
velocity;

12. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Compare and contrast speed and
velocity;

13. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Define acceleration;

14. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Determine the acceleration of a moving
object;

15. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Determine the average speed and
average velocity of a moving object;

16. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Compute for the distance, displacement,
speed, velocity, and acceleration of a
moving object;

17. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Solve problems involving constant and
uniformly accelerated motion in one
dimension;

18. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Evaluate and interpret visual
representations of the motions of objects;

19. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Create and interpret visual
representations of the motion of objects;

20. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Enumerate some technologies that make
use of motion detectors and explain or
describe their applications;

21. OBJECTIVE OF THE LESSON:
At the end of the lesson, I will be able to:
• Discuss road safety measures using the
concepts of motion.

22. WHEN CAN YOU SAY THAT AN OBJECT IS
IN MOTION?

23. Consider a book that is placed
on a table. Is it moving or not?

24. Most fail to recognize that the
question is incomplete. If you
answered that the book is not
moving, how can that be when
Earth is moving and the book is
on Earth?

25. If you answered that the book is
moving, how come it stays
exactly where it is?

26. The point is motion is relative. In
order for us to assert if an object
is in motion, we need to identify
a reference point.

27. If we use the ground or Earth as
the reference point, then the
book is not moving. However, if
we use the sun or the universe
as our reference point, then the
book is moving.

28. REFERENCE POINT
A reference point is defined as the starting
point (origin) for measuring motion.

29. HOW DO WE DESCRIBE THE MOTION OF
AN OBJECT?

30. To describe the motion of an
object, there must be a change in
the position (x) with respect to a
reference point. A position or
location must be specified at all
times from a reference point.

31. MOTION
Motion may be defined as a
continuous change in position with
respect to a reference point.

32. SCALAR QUANTITY
VERSUS
VECTOR QUANTITY

33. A scalar quantity is a physical quantity
that is expressed only in terms of its
magnitude and unit. While a vector
quantity is a physical quantity that
require both magnitude and direction
for their specification.

34. SCALAR QUANTITY
A scalar quantity is a physical quantity that
is expressed only in terms of its magnitude
and unit.

35. SCALAR QUANTITY
It is described with a single number
(including any units) indicating size,
magnitude, or dimension. Other common
scalars are temperature, mass, volume,
time, speed, and distance.

36. SCALAR QUANTITY
Symbol Name Example
d Distance 30 m
v Speed 50 m/s
t Time 15 s
E Energy 2,000 J

37. VECTOR QUANTITY
A vector quantity is a physical quantity that
require both magnitude and direction for
their specification. Because direction is an
important characteristic of vector, arrows
are used to represent them.

38. VECTOR QUANTITY
The fundamental distinction between scalar
and vector quantities is the characteristic of
direction. Oftentimes, cardinal points such
as north, south, west, and east are used to
specify direction.

39. VECTOR QUANTITY
Symbol Name Example
x Displacement 30 m north
v Velocity 50 m/s west
F Force 100 N up
a Acceleration 12 m/s2 down

40. ASSESSMENT:
1.) 50 km/h
2.) 80 km/h West
3.) 600 km
4.) 220 km 30⁰NE
5.) 12 km from home to market

41. DISTANCE
VERSUS
DISPLACEMENT

42. Distance is defined as the total
path length covered by an object
from one point to another. While
displacement is the measure of an
object’s change in position relative
to a reference point.

43. DISTANCE
Distance is defined as the total path length
covered by an object from one point to
another. It is scalar quantity that does not
require direction.

44. One Sunday morning, peter was going to
church. To get to the church from his
house, Peter needs to walk along a straight
path. As he was walking 50 meter east, he
noticed that he dropped his handkerchief
along the way, so he walked back again 20
meter west to fetch it. What was the total
distance that he traveled?

45. DISPLACEMENT
Displacement is the vector counterpart of
distance which requires direction. It is the
measure of an object’s change in position
relative to a reference point.

46. DISPLACEMENT
In symbols, this can be written as:
∆𝑥 = 𝑥𝑓 − 𝑥𝑖
where:
𝑥𝑓 = final position of the object,
𝑥𝑖 = initial position of the object

47. DISPLACEMENT
The symbol ∆ (Greek letter delta)
means change in. Thus ∆𝑥 means the
difference between the final and the
initial position of the object.

48. The SI unit for displacement is also the meter.
Displacement is a vector quantity, wherein its
direction must be carefully considered.

49. Because you are dealing with
motion in one dimension (i.e., along
a line), vectors pointing to the right
(toward the east) or upward (north)
are conventionally assigned a
positive sign,

50. whereas vectors pointing to the left
(toward the west) or downward
(south) are assigned a negative
sign.

51. One Sunday morning, peter was going to
church. To get to the church from his
house, Peter needs to walk along a straight
path. As he was walking 50 meter east, he
noticed that he dropped his handkerchief
along the way, so he walked back again 20
meter west to fetch it. What was his
displacement?

53. PRACTICE NO. 1:
A car moves 70 m east, then moves
120 m west, and finally moves east
again a distance of 90 m. If east is
chosen as the positive direction, what
is total distance that the car traveled
and the car’s resultant displacement?

54. PRACTICE NO. 2:
A car travels 30 kilometers (km) north
and turns east, and continues to travel
for another 40 km. What is the total
distance traveled by the car and the
displacement of the car with respect to
its starting point?