MDCAT Physics chapter 6: Physics · Waves and oscillations MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

27 exam-style questions on Physics · Waves and oscillations, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.

27 questions · 3 topics · 10 per test

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What chapter 6 covers

Ten Physics · Waves and oscillations questions with answers

Try each one, then open the answer. These ten stay the same; the test draws new ones every time.

1. Sound travels fastest through

  1. A
    steel
  2. B
    water
  3. C
    air
  4. D
    hydrogen gas
Show answer

Answer: A. Sound is fastest in solids, slower in liquids and slowest in gases: roughly 5000 m s−1 in steel, 1500 m s−1 in water and 340 m s−1 in air.

2. A transverse wave is to travel at 40 m s−1 along a string of mass per unit length 5.0 g m−1. Using v = √(T/μ), the tension needed is

  1. A
    8.0 × 103 N
  2. B
    8.0 N
  3. C
    0.20 N
  4. D
    200 N
Show answer

Answer: B. T = μv2 = (5.0 × 10−3)(40)2 = 8.0 N. Keeping μ in grams per metre gives 8.0 × 103 N, and forgetting to square v gives 0.20 N.

3. A wave of frequency 50 Hz travels at 30 m s−1. The phase difference between two points on it, 10 cm apart along the direction of travel, is

  1. A
    π/6 rad
  2. B
    π/3 rad
  3. C
    2π/3 rad
  4. D
    π/2 rad
Show answer

Answer: B. λ = v/f = 30/50 = 0.60 m, so the phase difference = (2π/λ) × 0.10 = 2π/6 = π/3 rad. π/6 rad forgets the 2 in 2π/λ.

4. At the same temperature and pressure, the speed of sound in hydrogen (molar mass 2 g mol−1) is how many times its speed in oxygen (molar mass 32 g mol−1)? Both are diatomic gases.

  1. A
    4
  2. B
    16
  3. C
    1/4
  4. D
    2
Show answer

Answer: A. v = √(γP/ρ). At the same pressure and temperature the density is proportional to the molar mass, and γ is the same for both diatomic gases, so vH/vO = √(32/2) = 4. 16 forgets the square root.

5. A mass–spring oscillator and a simple pendulum are set oscillating inside a satellite orbiting the Earth, where everything is weightless. Which statement is correct?

  1. A
    the pendulum swings normally, but the spring system does not oscillate
  2. B
    both oscillate, but with periods longer than on the Earth
  3. C
    the spring system oscillates normally, but the pendulum does not swing
  4. D
    both oscillate with the same periods as they had on the Earth
Show answer

Answer: C. T = 2π√(m/k) does not involve g, so the spring system still oscillates as before. A pendulum needs a restoring component of weight; with effective g = 0 there is none, so it does not swing (T = 2π√(l/g) becomes infinite).

6. A crest and a trough of equal size and shape travel towards each other along a string. At the instant they exactly overlap, the string

  1. A
    is momentarily straight, but its particles are moving
  2. B
    is straight and all its particles are momentarily at rest
  3. C
    shows a single crest of twice the height
  4. D
    has lost the energy of both pulses for good
Show answer

Answer: A. The displacements cancel (y1 + y2 = 0), so the string is momentarily straight, but the particle velocities add, so the energy is all kinetic at that instant. The pulses then pass through each other unchanged.

7. A pendulum swinging in air gradually comes to rest. The energy of its oscillation is

  1. A
    destroyed by air resistance and friction
  2. B
    stored as extra potential energy of the bob
  3. C
    converted into heat by air resistance and friction
  4. D
    given back to the bob as kinetic energy
Show answer

Answer: C. Air resistance and friction at the support do negative work, turning the energy of oscillation into heat (internal energy); energy is never destroyed. This steady loss of amplitude is called damping.

8. A listener walks quickly towards a stationary source of sound in still air. Compared with when he stands still, the sound he receives has

  1. A
    a shorter wavelength, and so a higher frequency
  2. B
    the same wavelength, but more waves reach him each second
  3. C
    the same wavelength and the same frequency
  4. D
    a longer wavelength, but a higher frequency
Show answer

Answer: B. The source is at rest, so the waves in the air keep their wavelength. Moving into the waves, the listener meets more wavefronts per second, so the frequency he hears is higher: f′ = f(v + uo)/v.

9. A graph of the potential energy of a mass–spring oscillator against its displacement from the mean position is

  1. A
    a parabola with its maximum at the mean position
  2. B
    a straight line passing through the origin
  3. C
    a horizontal straight line
  4. D
    a parabola with its minimum at the mean position
Show answer

Answer: D. P.E. = ½kx2, a parabola that is zero at x = 0 and greatest at the extreme positions. The kinetic energy graph is the inverted parabola, greatest at the mean position.

10. A train sounding a 480 Hz whistle passes a person standing on a platform at a steady 68 m s−1. Taking the speed of sound as 340 m s−1, the frequencies the person hears as the train approaches and then as it moves away are

  1. A
    576 Hz, then 384 Hz
  2. B
    400 Hz, then 600 Hz
  3. C
    600 Hz, then 400 Hz
  4. D
    600 Hz, then 360 Hz
Show answer

Answer: C. Approaching: f′ = fv/(v − us) = 480 × 340/272 = 600 Hz. Receding: f′ = fv/(v + us) = 480 × 340/408 = 400 Hz. 576 Hz and 384 Hz come from the formula for a moving listener, which does not apply when the source moves.

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Ways to practise this chapter

Physics · Waves and oscillations: questions students ask

How many Physics · Waves and oscillations MCQs are there?

27, each with the answer and a short explanation, across 3 topics: Simple harmonic motion, Progressive waves, Stationary waves and sound. Every chapter test draws ten of them, so you can take it many times.

Is the MDCAT Physics chapter 6 test free?

Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.

How is the chapter test marked?

The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.

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