force and motion

1. Lesson one :
Motion in one direction
Unit one
Forces and Motion

2. THE MOTION:
 Motion is the change of objects position as time passes
according to the location of another object.
 The path of a moving object may be straight, curved or
combination of each . If the path of the movement is straight
then we call it motion in straight line one direction.
 The simplest type of motion: the motion in a straight line in one
direction.
 The motion of the train or metro is considered from the motion in
one direction ,in this movement the train moves forward or
backward,
.

3. SPEED
 HOW CAN WE DESCRIBE THE MOTION OF THE OBJECT??
 To compare the movement of the objects we should refer to physical
quantity to describe the motion of object , this quantity is called speed .
 Speed : It is the distance covered by an object in a unit time
or the rate of change of distance.
- To measure the speed you need to measure time and distance ( the
length of path )
V = d/t so d = v X t t = d/v
Measuring units of speed :
-Meter / second
-Kilometer / Hour (in case of cars
trains, planes and ships).
Problems :
-A sprinter runs at a speed of 6 m/sec find
the distance covered in 10 second.
d = v X t d= 6×10 = 60 meters

4.  When car ( B ) covers the smaller distance than car (A )
at the same time span, therefore car (A) will be faster
than car ( B).
- This means that the speed of object is directly proportional
with covered distance at constant time.
 When car ( A ) Covers the same distance as car (B) in
shorter time span , therefore car ( A) will be faster than
car ( B ).
-This means that the speed of the object is inversely
proportional with time at constant distance .

5. *If the speed is constant the distance is directly
proportional with time
* FROM PREVIOUSE :TWO FACTORS ARE USED TO
DESCRIBE THE MOTION ( SPEED) : Distance and Time
* WHEN THE FOLLOWING HAPPENS:
The amount of speed is equal the amount of the
distance covered
When the object covers this distance through a
unit of time ( 1 hour or 1 minute or 1 second )