1. Lesson (1) Unit (1) Prep (2) Made by: Dr. Niveen Fawzy
Oscillatory Motion
Lesson (1) Unit (1) Prep (2)
Made by:
Dr. Niveen Fawzy

2. Motion & its types
Motion: It’s the change in an object’s position as time passes.
Types of motion
1- Translational motion
2- Periodic motion
First Translational motion
Its the motion in which the object’s position is changed relative to a fixed point (or a fixed frame of reference) from time to time between initial & final positions

3. Examples on translational motion
A person’s motion
A bicycle’s motion
A car’s motion
Train’s motion

4. Second: Periodic motion
It’s a motion which is repeated regularly in equal periods of time {moves periodically back & forth over the same path }
N.B : It doesn’t have initial & final positions
Examples of periodic motion
1-Oscillatory(vibrational) motion
2- Circular motion
3- Wave motion

5. Concept of Oscillatory Motion
Steps:
-Push with your hand gently the pendulum & leave it &use stopwatch to record time taken by pendulum to repeat its movement several times
Observation:
It will move on both sides around its original position (A)
The displacement of oscillating body around its original position are equal
This motion is repeated in equal time interval
-Maximum velocity is at point (A) & decreases gradually when it goes away from point (A), so maximum KE at point (A)
Conclusion
The oscillatory body moves around its rest point & repeated at equal time intervals

6. Oscillatory motion

7. Note that: Application for oscillatory motion
The movement of earth’s crust during earthquakes is considered an oscillatory motion
While ,
The motion of rotary bee is a periodic motion but not considered an oscillatory motion because its not repeated on the 2 sides of its rest point
Application for oscillatory motion
Microwave oven:
Its function depend on the vibration of water
molecules in food by effect of microwaves.
This oscillatory motion causes the collision
of water molecules & this increases its heat
Energy in very short time so food is cooked
faster

8. Give reason
Food must be put in glass , pottery or ceramic pots while metallic pots are not used
Because metallic pots reflect microwaves

9. Graphical representation of oscillatory motion
Tools:
-Spring -weight-holder-pencil
Steps:
1- Fix pencil to weight , then tie one end to spring
2- let the pencil’s tip touch the mid point of paper tape Roll the paper tape regularly , pull the weight downwards & leave it
Observation:
The pencil draws the shape of oscillatory motion
Conclusion:
The simple harmonic motion is the simplest oscillatory motion

10. The concepts related to oscillatory motion
1- Amplitude Complete oscillation
3- Periodic time Frequency
First: Amplitude
It’s the maximum displacement done by the oscillating body away from its original position {How far away an oscillating body can get from center}
Maximum displacement in a pendulum:
AB = BA = BC = CB
Each of them is an amplitude
Measuring unit (cm) or (m)
What is meant by: The amplitude of an oscillating body is 2cm
The maximum displacement away from its original position is 2cm

11. Second: Complete oscillation

12. Third: Periodic time

13. Fourth: Frequency:

15. Problems :

16. Problem :

17. Problems:

18. Model answers of book lesson(1) unit(1)

20. Question (5):
X is the motion of string
Y is the motion of spring
Z is the motion of pendulum