• 10.1 Simple Harmonic Motion (SHM)
• 10.2 Damped Oscillations
• 10.3 Wave Motion
• 10.4 Types of Mechanical Waves
• 10.5 Ripple Tank

FBISE Class 10 Physics - Chapter 10: Simple Harmonic Motion and Waves

10 Concept-Based Questions per Section

Section 10.1 - Simple Harmonic Motion (SHM)

1. What is Simple Harmonic Motion? State the two necessary conditions a body must fulfill to execute SHM.
2. Restoring Force: Why must the restoring force in SHM always be directed toward the mean (equilibrium) position? What happens to the motion if this condition is not met?
3. Pendulum vs. Spring: A simple pendulum and a mass-spring system both perform SHM. What physical quantity acts as the restoring force in each case?
4. Amplitude and Energy: How does the total mechanical energy of a body in SHM depend on its amplitude? If the amplitude is doubled, what happens to the total energy?
5. Period of a Pendulum: The time period of a simple pendulum is given by T = 2π√(L/g). If the length of the pendulum is increased four times, how does the time period change? Explain conceptually.
6. Displacement and Acceleration: In SHM, the acceleration is directly proportional to the displacement but opposite in direction (a ∝ -x). What does this mean physically at the extreme position and at the mean position?
7. Mass Effect on a Pendulum: A student claims that doubling the mass of the bob of a simple pendulum will double its time period. Is this correct? Justify your answer using the time period formula.
8. Energy Transformation: Describe the continuous transformation between kinetic energy (KE) and potential energy (PE) during one complete oscillation of a mass-spring system.
9. Ball-in-Bowl System: Explain how a ball rolling inside a smooth hemispherical bowl demonstrates SHM. Identify the mean position and the restoring force.
10. Frequency and Period Relationship: A body completes 50 vibrations in 10 seconds. Calculate its frequency and time period. Why is the product of frequency and time period always equal to 1?

Section 10.2 - Damped Oscillations

1. Definition of Damping: What are damped oscillations? Explain why all real-world oscillations are eventually damped rather than continuing forever.
2. Role of Friction: How does friction cause the amplitude of a vibrating body to decrease over time? Where does the mechanical energy go?
3. Examples in Daily Life: Give two examples from everyday life where damping is useful (beneficial) and two examples where it is undesirable.
4. Amplitude vs. Time: Sketch (or describe) how the amplitude of a damped oscillator changes over time. Is the frequency affected by damping in a simple pendulum?
5. Air Resistance and Pendulum: A pendulum swings in air and eventually stops. Identify all the damping forces acting on it, and explain the energy conversion that occurs.
6. Under-damping vs. Over-damping: Distinguish conceptually between an under-damped system (oscillates with decreasing amplitude) and an over-damped system (returns to equilibrium without oscillating). Give a real-life example of each.
7. Shock Absorbers: Car shock absorbers are designed to critically damp vibrations. Why is critical damping preferable to under-damping in this application?
8. Reducing Damping: A scientist wants to reduce damping in a vibrating system used for precision measurements. What two changes could be made to the setup to minimize energy loss?
9. Energy in Damped Oscillations: In a damped system, the total mechanical energy decreases with each oscillation. What happens to this energy? Is energy conserved overall? Explain.
10. Comparison with SHM: How does the graph of displacement vs. time for damped oscillations differ from that of ideal (undamped) SHM? What does this tell you about the two systems?

Section 10.3 - Wave Motion

1. Energy Transfer Without Matter Transfer: Waves transfer energy from one place to another without transferring matter. Explain this statement using the example of a water wave. What actually moves in such a wave?
2. Defining Wave Parameters: Define the following terms with reference to a wave: (a) wavelength (λ), (b) frequency (f), (c) time period (T), (d) amplitude (A).
3. Wave Speed Equation: Derive the relationship v = fλ between wave speed (v), frequency (f), and wavelength (λ). What does this tell you about the relationship between frequency and wavelength at constant wave speed?
4. Frequency and Wavelength Trade-off: A wave travels through a medium at a fixed speed. If its frequency is doubled, what happens to its wavelength? Justify your answer conceptually.
5. Methods of Energy Transfer: How many methods are there to transfer energy from one place to another? Name and briefly describe each, giving one example.
6. Wave Properties - Reflection: When a wave hits a hard boundary (e.g., a wall), it reflects. State two things that remain unchanged after reflection and one thing that changes.
7. Refraction of Waves: A water wave moves from deep water into shallow water. Its speed decreases. Using v = fλ, explain what happens to the wavelength. Does the frequency change? Why or why not?
8. Diffraction of Waves: What is diffraction? Under what condition does significant diffraction occur through a gap or opening? Why does sound bend around corners more easily than light?
9. Numerical Problem: 100 waves pass through a fixed point in 20 seconds. The wavelength is 6 cm. Calculate: (a) frequency, (b) time period, (c) wave speed.
10. Interference - Constructive vs. Destructive: Differentiate between constructive and destructive interference. What conditions on path difference lead to each type?

Section 10.4 - Types of Mechanical Waves

1. Transverse vs. Longitudinal Waves: Define transverse and longitudinal waves. In each type, what is the relationship between the direction of particle vibration and the direction of wave propagation?
2. Compressions and Rarefactions: In a longitudinal wave, explain what compressions and rarefactions are. How do they relate to the pressure and density of the medium?
3. Examples Classification: Classify each of the following as transverse or longitudinal: (a) sound waves in air, (b) waves on a stretched string, (c) light waves, (d) seismic S-waves.
4. Medium Requirement: Can mechanical waves travel through a vacuum? Explain why or why not. How does this differ from electromagnetic waves?
5. Wavelength in Longitudinal Waves: In a longitudinal wave, how is one complete wavelength (λ) defined in terms of compressions and rarefactions?
6. Speed in Different Media: Mechanical waves generally travel faster in solids than in gases. Explain why, linking your answer to the elastic properties and density of the medium.
7. Stationary (Standing) Waves: What are stationary waves? How are they formed? Distinguish between nodes and antinodes.
8. Distance Between Nodes: In a stationary wave, what is the distance between two neighboring nodes expressed in terms of wavelength (λ)? What about the distance between a node and the nearest antinode?
9. String Waves: A student plucks a stretched string. Describe the type of wave produced and explain how nodes form at the fixed ends of the string.
10. Comparison Table: Create a comparison between transverse and longitudinal waves covering: direction of vibration, examples, ability to travel in vacuum, and representation.

Section 10.5 - Ripple Tank

1. Purpose of a Ripple Tank: What is a ripple tank and what is it used for in physics? Describe its main components (vibrator, water tray, light source, screen).
2. Crests and Troughs on Screen: When light passes through the ripple tank, bright lines appear on the screen below. Do these bright lines represent crests or troughs of the wave? Explain the optics behind this.
3. Demonstrating Reflection: How can the reflection of waves be demonstrated using a ripple tank? What type of barrier is placed in the tank, and what is observed?
4. Demonstrating Refraction: Describe how refraction is demonstrated in a ripple tank. What change is made to the tank to alter the wave speed, and how do the wave patterns change?
5. Demonstrating Diffraction: How is diffraction demonstrated in a ripple tank? What do you observe on the screen when: (a) the gap is much larger than the wavelength, and (b) the gap is nearly equal to the wavelength?
6. Demonstrating Interference: Two point sources vibrating in phase are placed in a ripple tank. Describe the interference pattern that appears on the screen. What causes the alternating regions of calm water and large disturbance?
7. Effect of Frequency on Wavelength: In a ripple tank, if the frequency of the vibrator is increased while the water depth stays the same, what change is observed in the wave pattern? Justify using v = fλ.
8. Shallow vs. Deep Water: When waves in a ripple tank pass from a deeper region into a shallower region, the waves slow down and the wavelength decreases. Does the frequency change? What does this demonstrate about wave behavior?
9. Measuring Wave Speed: Describe how you would use a ripple tank experimentally to determine the speed of water waves. What measurements would you need to take?
10. Practical Application: The ripple tank is a model used to study wave behaviors. Name three real-world wave phenomena (involving sound, light, or water) that can be better understood by observing their analogues in a ripple tank.

Summary Table