Motion in one direction 1

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 combinatio n 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 t rain 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 )