CHAPTER # 10

SIMPLE HARMONIC MOTION AND WAVES

Multiple Choice Question (MCQs)

                         i.            The Motion of a simple pendulum is an example of simple harmonic motion.
  ii.            The period of a simple pendulum does not depend on mass so it remains the same.
 iii.            A helical spring (slinky) is used to produce both transverse and longitudinal waves.
  iv.            Waves transfer Energy.
    v.            Conduction, radiation, and wave motion are all methods of energy transfer.
  vi.            Electromagnetic waves in a vacuum have the same speed.
vii.            Frequency=30Hz, no. of waves=25, wavelength=50cm, so velocity will be 60cm/sec.
viii.          Amplitude is independent of others.
     ix.          v = fʎ

REVIEW QUESTIONS 

10.1 Simple harmonic motion and its necessary conditions.

The oscillatory motion of a body is simple harmonic if its acceleration is directly proportional to the displacement and is directed towards the mean position.

Conditions

                           i.      Acceleration is directed towards the mean position.
      ii.    Acceleration is directly proportional to displacement.
    iii.   The body always vibrates about its fix position.

10.2 Examples of simple harmonic motion (SHM) in daily life.

  1.                     Bungee jumping.
  2.                    Cradle.
  3.                     Pendulum.
  4.                     Swing.
  5.                      Hearing.

10.3 Damped Oscillations and how it progressively reduces the amplitude?

"Damped oscillations are vibrations that decrease the amplitude of motion with time." The friction force is always resisting the motion of the system, which reduces the mechanical energy of the system over time. This is why damping reduces the amplitude progressively.

10.4 What is a wave? Also, differentiate between mechanical and electromagnetic waves with examples.

Wave

It is a disturbance in the medium that causes vibratory motion about the mean position at equal time intervals.

Mechanical wave

Electromagnetic wave

Waves that require a medium to propagate. For instance; waves produce in spring, water waves.

Wave that does not require a medium for their propagation. For instance; X-Rays, Radio waves.


 10.5 Differentiate between longitudinal and transversal waves with examples.

Longitudinal wave

Transverse wave

·     The wave in which particles move back and forth along the direction of propagation of the wave is known as a transverse wave.

·         It has compression and rarefaction.

·         A sound wave is an example of it.

·      The wave in which particles of the medium vibrate perpendicularly to the direction of motion of the wave.

·         It has a crest and trough.

·         A water wave is an example of it.

10.6 Draw a transverse wave of 2cm amplitude and 4 cm wavelength. Also, label a crest and trough on it.

Shows the crest, trough, wavelength and amplitude.


10.7 Relationship between velocity, frequency, and wavelength of a wave.

Shows the derivation and relation between frequency, velocity and wavelength.

10.8 Justify that waves are the means of energy transfer without the transfer of matter.

Drop a stone into a pond. Waves will be produced on the surface of the water and will travel outwards. Place a wooden block at some distance from the falling stone. When waves reach the block, the energy from the waves causes it to move up and down with the motion of the water particles.

10.9 With reference of the ripple tank explain the following.

Reflection

Refraction

Diffraction

Place the barrier at an angle to the wavefront in the ripple tank. Water waves will reflect from it in such a way that the angle of the incident wave equals the angle of reflection.

The direction of travel of water waves in a ripple tank changes as they pass from one medium to another. Refraction is the process by which the path of water waves changes from deep to shallow.

When water waves pass through a small slit between two obstacles, they spread in all directions in the shape of semicircles. This is referred to as diffraction.

10.10 Does wavelength increase if the frequency of wave increases?

No, the wavelength will not increase if the frequency increases because both wavelength and frequency have an inverse relation. Due to this, if frequency increases the wavelength will decrease.

CONCEPTUAL QUESTIONS

10.1 What will be the change in its period? If the length of a simple pendulum is doubled.  

shows the relation of time period and length.

10.2 Is the motion of the ball simple harmonic? If it drops from a certain height to the floor.

No, the motion of this ball is not simple harmonic because, for SHM, a body must always vibrate about a fixed position, which does not occur in this case.

10.3 Why the time period did not change with the change in the masses of bobs of the pendulum?

elaborate the relation of length and mass.

10.4 Which type of wave does not require any material medium for its propagation?

The propagation of an electromagnetic wave is not dependent on any material medium. Because it is made up of both magnetic and electric fields. Radio waves, X-rays, television waves, heat, and light waves are all examples.

10.5 What change occurs in the speed of the waves? When waves move from deep to shallower water.

From relation v = fʎ, speed is directly proportional to wavelength if the frequency is constant. When water waves enter from deep to shallower water, their wavelength decreases so, the speed will also decrease.


THANKS!  

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