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Lesson 3 Wave motion
1st Relative motion:
What do you observe in the following cases:
* You feel that the two cars are not moving
( no moving will be observed)
2. A car moves against your direction.
* You feel that the other car moves with a high speed.
[ The sum between their speeds]
3. You move beside a stopping car.
* You feel that the other car is moving backwards.
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Relative motion: It is the change in an object position or direction with the time passes relative to another object or a fixed point known as a frame of reference.
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2nd Types of motion:
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Periodic motion |
Transitional motion |
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1. It is a motion which is regularly repeated in equal periods of time.
Examples: 1. Vibrating motion: as in the simple pendulum.
2. Circular motion: as a fan arm while it is on. 3. Wave motion: as when a piece of cork is thrown in water. |
1. It is a motion in which the object's position is changed relative to a fixed point from time to time. 2. It has initial & final position.
Examples:
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3rd Applications on wave motion
Give reasons:
Although the thunder& lightning happens at the same time just before raining, we see Lightning before hearing thunder.
Because the speed of light is greater than the speed of sound.
which needs a medium to travel through it as air.
known as electromagnetic wave which don't need a medium
to travel through it.
Waves
Waves are divided into two types:
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Mechanical waves |
Electromagnetic waves |
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1.They are produced by the vibration of the medium particles.
2. They need a medium to transfer through. Edd 3. Their speed is relatively low. (speed of sound is about 340 m/s)
Examples Fffd Sound waves Water waves |
1.They are accompanied by electric and magnetic Fields.
2. They spread in all media and space.
3.Their speed is very high (speed of light is about 300 million m/s Examples .Light waves -X-ray .Radio& T.V. waves .Wireless wave - U.V ray .Infrared rays |
1st Some technological applications for Mechanical waves :
1. Examining& curing sets for human body using sound waves.
2. Stringed musical instruments as violin& guitar.
3. Amplifiers& controlling sound's sets.
2nd Some technological applications of electromagnetic waves:
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The ray |
Applications |
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Visible light ( seen) |
* Photographic cameras. - T.V cameras – data shows.
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X- rays |
* Detecting the bone fracture – examining mineral raw in industry (to show errors, pores & cracks) |
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Gamma rays |
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Ultraviolet rays UV |
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Infrared rays I R |
* Cooking food as they have heat effect - In remote sets to control electric sets(T.V, DVD,…)
using satellites – Night vision sets in military. |
Graphing motion
* When an object moves in a straight line, the displacement occurred to
the object changes with the time passes from the object original position.
If the displacements which occurred every second are equal, it is
represented by a straight line passing through the original point.
2. The non- uniform velocity:
If the displacements occurred every second are not equal, it is
represented by curved line passing through the original point.
3. The static state ( no motion):
If the displacement value is fixed (it doesn't change
with time passes), it is represented by a straight line
parallel to the axis of time.
It is the distance at which an object moves away from its original position at any moment.