Prep.2 Unit One - Lesson One PDF

Science Mr. Ahmed Elbasha Prep.2 Second Term Unit One – Lesson One Oscillatory Motion Name : ------------------------------ 1 Mr.Ahmed ElBasha Mob.: 01153233911  Periodic motion: It is a motion, which...

Science Mr. Ahmed Elbasha Prep.2 Second Term Unit One – Lesson One Oscillatory Motion Name : ------------------------------ 1 Mr.Ahmed ElBasha Mob.: 01153233911  Periodic motion: It is a motion, which is regularly repeated in equal periods of time.  The concept of oscillatory motion: Observations: 1. The oscillating body moves on both sides around its rest position. This motion is repeated in equal time intervals. 2. The displacements of the oscillating body around its rest position are equal. 3. The velocity of the oscillating body reaches its maximum value when it passes its rest position and decreases gradually when it goes far from it until it reaches zero at the maximum displacement on both sides of rest position. Conclusion: The oscillating body moves around its rest position, where the motion is repeated through equal intervals of time which is known as "Oscillatory motion". Oscillatory motion: It is the periodic motion of the oscillating body around its rest point, where the motion is repeated through equal intervals of time. Relation between the velocity of an oscillating body and its kinetic energy: The kinetic energy of an oscillating body is directly proportional to: The mass of the oscillating body. The squared velocity of the oscillating body. So, the kinetic energy increases when the velocity of the oscillating body increases and vice versa (assuming that it’s mass is not changed). 2 Mr.Ahmed ElBasha Mob.: 01153233911 The following figure refers to the application of the concept of oscillatory motion on the motion of the spring: Examples of oscillatory motion: 3 Mr.Ahmed ElBasha Mob.: 01153233911   Graphical representation of the oscillatory motion: The oscillatory motion of the spring can be represented graphically as shown in the following activity: Observation: The pencil draws the shape of the oscillatory motion on the paper tape as shown in the figure. Conclusion: Motion of the weight which is called the simple harmonic motion is considered the simplest form of oscillatory motion.  Properties of oscillatory motion:  Amplitude: Amplitude: It is the maximum displacement done by the oscillating body away from its rest position. The measuring unit of the amplitude is metre (m). 4 Mr.Ahmed ElBasha Mob.: 01153233911   Complete oscillation: Complete oscillation: It is the motion of an oscillating body when it passes by a fixed point on its path two successive times in the same direction. The following graph refers to the relation between the displacement and the time taken for a simple harmonic motion of a simple pendulum. 5 Mr.Ahmed ElBasha Mob.: 01153233911   Periodic time (T):  Frequency: 6 Mr.Ahmed ElBasha Mob.: 01153233911 The following chart shows the conversions of these fractions: The relation between periodic time and frequency: From the previous explanation, we conclude that: The frequency of an oscillating body is the reciprocal of the periodic time. Frequency is inversely proportional to the periodic time. (i.e. frequency decreases by increasing the periodic time and vice versa) 7 Mr.Ahmed ElBasha Mob.: 01153233911