Science 7 - Describing Motion

Motion is defined
as the change in
position over an
interval of time.

 What is a point
of reference?

 A point of reference is
something that seems
steady that is used to
compare the position of an
object.

Differentiate
distance from
displacement.

Displacement will be
defined as measurement
of length plus direction. It
refers to the shortest
distance between the
object’s two positions.

Displacement measures
the length of the straight
line that connects the
object’s point of origin
and its point of
destination.

Distance refers to
the length of the
entire path that the
object travelled.

What is the
minimum and
maximum speed
limit in the
Philippines?

The minimum speed limit in
the Philippines is 60 km/h
and the maximum speed
limit is 100 km/h.

Speed is defined as
distance travelled divided
by the time of travel.

The units of speed can
be miles per hour
(mi/h), kilometers per
hour (km/h), or
meters per second (m/s).

What is speed?
What is
direction?

Speed with direction is
referred to as velocity.

Travellers Distance
(m)
Time
(s)
Speed
(m/s)
Chaerin 121 2500
Ms. Gong 35 0.30
Ms. Park 1900 0.05
Kim 21 0.10

Constant speed
vs.
Instantaneous
speed

If you solved for the distance
travelled by each participant
over the time he took to cover
such distance, then you have
computed for his average
speed. But why average speed
and not just speed?

It is considered average
speed because it
represents the speed of
the participant throughout
his travel.

During his travel, there
were instants that his
speed would vary. His
speed at an instant is
called instantaneous
speed .

Similarly, the velocity of a
moving body at an instant is
called instantaneous
velocity. The instantaneous
speed may be equal, greater
than, or less than the
average speed.

When an object’s
instantaneous speed values
are always the same, then it
means that the object is
moving with constant speed.
We refer to this as constant
motion.

Where you will be and
what time you will reach
your destination is easily
predicted when you move
at constant speed or
velocity.

Are you familiar
with the
speedometer?

Speedometer is a
device used to
measure the
instantaneous speed
of a vehicle.

How fast is the
velocity
changing?

Acceleration is introduced as
due to the change in the
speed of the moving object.
It may also be due to the
change in the direction of
the object.

Acceleration, by
definition, is the change in
velocity over a time
interval, and velocity is
known as speed plus
direction.

Let us summarize what you
have learned by relating
distance , displacement,
speed, velocity, and
acceleration.

If an object does not
change its position at a
given time interval, then
it is at rest or its speed is
zero or not accelerating.

If an object covers equal
distance at equal intervals
of time, then it is moving
at constant speed and still
not accelerating.

If an object covers varying
distances at equal intervals
of time, then it is moving
with changing speed or
velocity. It means that
the object is accelerating.

Science 7 - Describing Motion

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Science 7 - Describing Motion