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Page 1 K.V. Lumding; K.V. Karimganj; K.V. Langjing 187 Oscillations and Waves ? Periodic Motion: A motion which repeats itself over and over again after a regular interval of time. ? Oscillatory Motion: A motion in which a body moves back and forth repeatedly about a fixed point. ? Periodic function: A function that repeats its value at regular intervals of its argument is called periodic function. The following sine and cosine functions are periodic with period T. f(t) = sin and g(t) = cos These are called Harmonic Functions. Note :- All Harmonic functions are periodic but all periodic functions are not harmonic. One of the simplest periodic functions is given by f(t) = A cos ?t [? = 2p/T] If the argument of this function ?t is incre a se d b y a n int e g ral m u ltipl e o f 2 p rad ia n s, the value of the function remains the same. The function f(t) is then periodic and its period, T is given by T = Thus the function f(t) is periodic with period T f(t) = f(t +T) Linear combination of sine and cosine functions f(t) = A sin ?t + B cos ?t A periodic function with same period T is given as A = D cos ø and B = D sin ø Page 2 K.V. Lumding; K.V. Karimganj; K.V. Langjing 187 Oscillations and Waves ? Periodic Motion: A motion which repeats itself over and over again after a regular interval of time. ? Oscillatory Motion: A motion in which a body moves back and forth repeatedly about a fixed point. ? Periodic function: A function that repeats its value at regular intervals of its argument is called periodic function. The following sine and cosine functions are periodic with period T. f(t) = sin and g(t) = cos These are called Harmonic Functions. Note :- All Harmonic functions are periodic but all periodic functions are not harmonic. One of the simplest periodic functions is given by f(t) = A cos ?t [? = 2p/T] If the argument of this function ?t is incre a se d b y a n int e g ral m u ltipl e o f 2 p rad ia n s, the value of the function remains the same. The function f(t) is then periodic and its period, T is given by T = Thus the function f(t) is periodic with period T f(t) = f(t +T) Linear combination of sine and cosine functions f(t) = A sin ?t + B cos ?t A periodic function with same period T is given as A = D cos ø and B = D sin ø K.V. Lumding; K.V. Karimganj; K.V. Langjing 188 f(t) = D sin (?t + ø) D = v and ø = ? Simple Harmonic Motion (SHM): A particle is said to execute SHM if it moves to and fro about a mean position under the action of a restoring force which is directly proportional to its displacement from mean position and is always directed towards mean position. Restoring Force Displacement F W h e re ‘k’ is f o rce c o n s ta n t. ? Amplitude: Maximum displacement of oscillating particle from its mean position. x Max = ? Time Period: Time taken to complete one oscillation. ? Frequency: . Unit of frequency is Hertz (Hz). 1 Hz = 1 ? Angular Frequency: = 2 p? S .I u n it ? = ra d ? Phase: 1. The Phase of Vibrating particle at any instant gives the state of the particle as regards its position and the direction of motion at that instant. It is denoted by ø. 2. Initial phase or epoch: The phase of particle corresponding to time t = 0. It is denoted by ø. ? Displacement in SHM : ( ø 0 ) Where, = Displacement, A = Amplitude ?t = Angular Frequency ø 0 = Initial Phase. Page 3 K.V. Lumding; K.V. Karimganj; K.V. Langjing 187 Oscillations and Waves ? Periodic Motion: A motion which repeats itself over and over again after a regular interval of time. ? Oscillatory Motion: A motion in which a body moves back and forth repeatedly about a fixed point. ? Periodic function: A function that repeats its value at regular intervals of its argument is called periodic function. The following sine and cosine functions are periodic with period T. f(t) = sin and g(t) = cos These are called Harmonic Functions. Note :- All Harmonic functions are periodic but all periodic functions are not harmonic. One of the simplest periodic functions is given by f(t) = A cos ?t [? = 2p/T] If the argument of this function ?t is incre a se d b y a n int e g ral m u ltipl e o f 2 p rad ia n s, the value of the function remains the same. The function f(t) is then periodic and its period, T is given by T = Thus the function f(t) is periodic with period T f(t) = f(t +T) Linear combination of sine and cosine functions f(t) = A sin ?t + B cos ?t A periodic function with same period T is given as A = D cos ø and B = D sin ø K.V. Lumding; K.V. Karimganj; K.V. Langjing 188 f(t) = D sin (?t + ø) D = v and ø = ? Simple Harmonic Motion (SHM): A particle is said to execute SHM if it moves to and fro about a mean position under the action of a restoring force which is directly proportional to its displacement from mean position and is always directed towards mean position. Restoring Force Displacement F W h e re ‘k’ is f o rce c o n s ta n t. ? Amplitude: Maximum displacement of oscillating particle from its mean position. x Max = ? Time Period: Time taken to complete one oscillation. ? Frequency: . Unit of frequency is Hertz (Hz). 1 Hz = 1 ? Angular Frequency: = 2 p? S .I u n it ? = ra d ? Phase: 1. The Phase of Vibrating particle at any instant gives the state of the particle as regards its position and the direction of motion at that instant. It is denoted by ø. 2. Initial phase or epoch: The phase of particle corresponding to time t = 0. It is denoted by ø. ? Displacement in SHM : ( ø 0 ) Where, = Displacement, A = Amplitude ?t = Angular Frequency ø 0 = Initial Phase. K.V. Lumding; K.V. Karimganj; K.V. Langjing 189 Case 1: When Particle is at mean position x = 0 v = v = v max = = Case 2: When Particle is at extreme position x = v = v = 0 Acceleration Case 3: When particle is at mean position x = 0, acceleration = ( ) = 0. Case 4: When particle is at extreme position then acceleration = ? Formula Used : 1. ( ø 0 ) 2. v = v , v max = ?A. 3. ? 2 ( ø 0 ) a max = ? 2 A 4. Restoring force F = = m? 2 Where = force constant & ? 2 = 5. Angular freq. ? = 2 = / 6. Time Period T = 2pv = 2pv 7. Time Period T = 2pv = 2pv 8. P .E a t d ispl a ce m e n t ‘y ’ f r o m m e a n p o sitio n E P = ky 2 = m? 2 y 2 = m? 2 A 2 sin 2 ?t Page 4 K.V. Lumding; K.V. Karimganj; K.V. Langjing 187 Oscillations and Waves ? Periodic Motion: A motion which repeats itself over and over again after a regular interval of time. ? Oscillatory Motion: A motion in which a body moves back and forth repeatedly about a fixed point. ? Periodic function: A function that repeats its value at regular intervals of its argument is called periodic function. The following sine and cosine functions are periodic with period T. f(t) = sin and g(t) = cos These are called Harmonic Functions. Note :- All Harmonic functions are periodic but all periodic functions are not harmonic. One of the simplest periodic functions is given by f(t) = A cos ?t [? = 2p/T] If the argument of this function ?t is incre a se d b y a n int e g ral m u ltipl e o f 2 p rad ia n s, the value of the function remains the same. The function f(t) is then periodic and its period, T is given by T = Thus the function f(t) is periodic with period T f(t) = f(t +T) Linear combination of sine and cosine functions f(t) = A sin ?t + B cos ?t A periodic function with same period T is given as A = D cos ø and B = D sin ø K.V. Lumding; K.V. Karimganj; K.V. Langjing 188 f(t) = D sin (?t + ø) D = v and ø = ? Simple Harmonic Motion (SHM): A particle is said to execute SHM if it moves to and fro about a mean position under the action of a restoring force which is directly proportional to its displacement from mean position and is always directed towards mean position. Restoring Force Displacement F W h e re ‘k’ is f o rce c o n s ta n t. ? Amplitude: Maximum displacement of oscillating particle from its mean position. x Max = ? Time Period: Time taken to complete one oscillation. ? Frequency: . Unit of frequency is Hertz (Hz). 1 Hz = 1 ? Angular Frequency: = 2 p? S .I u n it ? = ra d ? Phase: 1. The Phase of Vibrating particle at any instant gives the state of the particle as regards its position and the direction of motion at that instant. It is denoted by ø. 2. Initial phase or epoch: The phase of particle corresponding to time t = 0. It is denoted by ø. ? Displacement in SHM : ( ø 0 ) Where, = Displacement, A = Amplitude ?t = Angular Frequency ø 0 = Initial Phase. K.V. Lumding; K.V. Karimganj; K.V. Langjing 189 Case 1: When Particle is at mean position x = 0 v = v = v max = = Case 2: When Particle is at extreme position x = v = v = 0 Acceleration Case 3: When particle is at mean position x = 0, acceleration = ( ) = 0. Case 4: When particle is at extreme position then acceleration = ? Formula Used : 1. ( ø 0 ) 2. v = v , v max = ?A. 3. ? 2 ( ø 0 ) a max = ? 2 A 4. Restoring force F = = m? 2 Where = force constant & ? 2 = 5. Angular freq. ? = 2 = / 6. Time Period T = 2pv = 2pv 7. Time Period T = 2pv = 2pv 8. P .E a t d ispl a ce m e n t ‘y ’ f r o m m e a n p o sitio n E P = ky 2 = m? 2 y 2 = m? 2 A 2 sin 2 ?t K.V. Lumding; K.V. Karimganj; K.V. Langjing 190 9. K .E . a t d ispla ce m e n t ‘ y ’ f rom t h e m e a n p o siti o n E K = k( ) = m? 2 (A 2 – y 2 ) = m? 2 A 2 cos 2 ?t 10. Total Energy at any point E T = kA 2 = m? 2 A 2 = 2p 2 mA 2 ? 2 11. Spring Factor K = F/y 12. P e ri o d O f o scil lat io n o f a m a ss ‘ m ’ su s p e n d e d f ro m a m a ssl e ss sp ri n g o f f o rce co n sta n t ‘ k’ T = 2p v For two springs of spring factors k 1 and k 2 connected in parallel effective spring factor k = k 1 + k 2 T=2p v + 13. For t w o sp ri n g s co n n e cte d in se ri e s, e ff e c tiv e sp ri n g f a cto r ‘k’ is g iv e n a s Or + T=2 v ( + ) Note:- When length of a spring is made ‘n’ times its spring factor becomes times and hence time period increases v times. 14. W h e n sp ri n g is cu t in to ‘n ’ e q u a l p iec e s, s p ri n g f a ct o r o f e a c h p a rt b e co m e s ‘nk’. v 15. Oscillation of simple pendulum v / v / 16. For a liq u id o f d e n sity ? co n t a ine d in a U -tube up to h e ig h t ‘h’ Page 5 K.V. Lumding; K.V. Karimganj; K.V. Langjing 187 Oscillations and Waves ? Periodic Motion: A motion which repeats itself over and over again after a regular interval of time. ? Oscillatory Motion: A motion in which a body moves back and forth repeatedly about a fixed point. ? Periodic function: A function that repeats its value at regular intervals of its argument is called periodic function. The following sine and cosine functions are periodic with period T. f(t) = sin and g(t) = cos These are called Harmonic Functions. Note :- All Harmonic functions are periodic but all periodic functions are not harmonic. One of the simplest periodic functions is given by f(t) = A cos ?t [? = 2p/T] If the argument of this function ?t is incre a se d b y a n int e g ral m u ltipl e o f 2 p rad ia n s, the value of the function remains the same. The function f(t) is then periodic and its period, T is given by T = Thus the function f(t) is periodic with period T f(t) = f(t +T) Linear combination of sine and cosine functions f(t) = A sin ?t + B cos ?t A periodic function with same period T is given as A = D cos ø and B = D sin ø K.V. Lumding; K.V. Karimganj; K.V. Langjing 188 f(t) = D sin (?t + ø) D = v and ø = ? Simple Harmonic Motion (SHM): A particle is said to execute SHM if it moves to and fro about a mean position under the action of a restoring force which is directly proportional to its displacement from mean position and is always directed towards mean position. Restoring Force Displacement F W h e re ‘k’ is f o rce c o n s ta n t. ? Amplitude: Maximum displacement of oscillating particle from its mean position. x Max = ? Time Period: Time taken to complete one oscillation. ? Frequency: . Unit of frequency is Hertz (Hz). 1 Hz = 1 ? Angular Frequency: = 2 p? S .I u n it ? = ra d ? Phase: 1. The Phase of Vibrating particle at any instant gives the state of the particle as regards its position and the direction of motion at that instant. It is denoted by ø. 2. Initial phase or epoch: The phase of particle corresponding to time t = 0. It is denoted by ø. ? Displacement in SHM : ( ø 0 ) Where, = Displacement, A = Amplitude ?t = Angular Frequency ø 0 = Initial Phase. K.V. Lumding; K.V. Karimganj; K.V. Langjing 189 Case 1: When Particle is at mean position x = 0 v = v = v max = = Case 2: When Particle is at extreme position x = v = v = 0 Acceleration Case 3: When particle is at mean position x = 0, acceleration = ( ) = 0. Case 4: When particle is at extreme position then acceleration = ? Formula Used : 1. ( ø 0 ) 2. v = v , v max = ?A. 3. ? 2 ( ø 0 ) a max = ? 2 A 4. Restoring force F = = m? 2 Where = force constant & ? 2 = 5. Angular freq. ? = 2 = / 6. Time Period T = 2pv = 2pv 7. Time Period T = 2pv = 2pv 8. P .E a t d ispl a ce m e n t ‘y ’ f r o m m e a n p o sitio n E P = ky 2 = m? 2 y 2 = m? 2 A 2 sin 2 ?t K.V. Lumding; K.V. Karimganj; K.V. Langjing 190 9. K .E . a t d ispla ce m e n t ‘ y ’ f rom t h e m e a n p o siti o n E K = k( ) = m? 2 (A 2 – y 2 ) = m? 2 A 2 cos 2 ?t 10. Total Energy at any point E T = kA 2 = m? 2 A 2 = 2p 2 mA 2 ? 2 11. Spring Factor K = F/y 12. P e ri o d O f o scil lat io n o f a m a ss ‘ m ’ su s p e n d e d f ro m a m a ssl e ss sp ri n g o f f o rce co n sta n t ‘ k’ T = 2p v For two springs of spring factors k 1 and k 2 connected in parallel effective spring factor k = k 1 + k 2 T=2p v + 13. For t w o sp ri n g s co n n e cte d in se ri e s, e ff e c tiv e sp ri n g f a cto r ‘k’ is g iv e n a s Or + T=2 v ( + ) Note:- When length of a spring is made ‘n’ times its spring factor becomes times and hence time period increases v times. 14. W h e n sp ri n g is cu t in to ‘n ’ e q u a l p iec e s, s p ri n g f a ct o r o f e a c h p a rt b e co m e s ‘nk’. v 15. Oscillation of simple pendulum v / v / 16. For a liq u id o f d e n sity ? co n t a ine d in a U -tube up to h e ig h t ‘h’ K.V. Lumding; K.V. Karimganj; K.V. Langjing 191 v / 17. For a body dropped in a tunnel along the diameter of earth v / , where R = Radius of earth 18. Resonance: If the frequency of driving force is equal to the natural frequency of the oscillator itself, the amplitude of oscillation is very large then such oscillations are called resonant oscillations and phenomenon is called resonance. Waves Angular wave number: It is phase change per unit distance. i.e. ? ? 2 ? k , S.I unit of k is radian per meter. Relation between velocity, frequency and wavelength is given as :- ?? ? V Velocity of Transverse wave:- (i )In so li d mole cu les h a v ing m o d u lus o f ri g idity ‘ ? ’ a n d d e n sity ‘?’ is ? ? ? V (i i) In st ri n g f o r m a ss p e r un it le n g th ’m ’ a n d te n sion ‘ T ’ is m T V ? Velocity of longitudinal wave:- (i) in solid ? Y V ? , Y = y o u n g ’ s m o d u lus (ii) in liquid ? K V ? , K= bulk modulusRead More
1. What are oscillations and waves? |
2. What is the difference between mechanical waves and electromagnetic waves? |
3. How are oscillations and waves related to each other? |
4. What are the different types of waves? |
5. How do waves exhibit properties like reflection, refraction, and diffraction? |
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