Physics: waves and explanations

Question 1 (1 mark)

Which quantity is the number of complete oscillations per second?

1. Amplitude
2. Period
3. Frequency
4. Wavelength

Question 2 (1 mark)

A wave has frequency 5.0 Hz and wavelength 0.80 m. What is its speed?

1. 4.0 m s⁻¹
2. 6.25 m s⁻¹
3. 0.16 m s⁻¹
4. 5.8 m s⁻¹

Question 3 (1 mark)

Which graph lets you read wavelength directly?

1. Displacement–time at one point
2. Speed–time of a source
3. Frequency–time of a source
4. Displacement–distance at one instant

Question 4 (1 mark)

Two equal, opposite displacements overlap at a point in a linear medium. What does superposition predict there at that instant?

1. Both waves disappear permanently
2. Zero resultant displacement
3. Twice the positive displacement
4. A permanent loss of all wave energy

Question 5 (3 marks)

A source makes 20 complete oscillations in 8.0 s. Calculate frequency and period, showing the relationship between them.

Question 6 (3 marks)

Distinguish longitudinal and transverse mechanical waves using particle motion, and explain how wave propagation differs from net transport of medium particles.

Question 7 (3 marks)

A displacement–time record at a fixed point has successive positive peaks at 0.20 s and 0.70 s. A spatial snapshot has adjacent peaks 1.2 m apart. Calculate period, frequency and wave speed.

Question 8 (3 marks)

In the data table, does frequency affect wave speed substantially? Calculate each speed and give a cautious conclusion.

Question 9 (3 marks)

At one point, two waves have simultaneous displacements +3 mm and −1 mm. Find the resultant displacement and explain why a zero resultant elsewhere would not demonstrate zero energy everywhere.

Question 10 (3 marks)

A sound source is heard across a room. Explain why a small parcel of air need not travel from the source to the listener, and why sound cannot propagate through an ideal vacuum.

Question 11 (4 marks)

Design a method to measure wave speed from frequency and wavelength on a wave apparatus. Explain four features that improve the quality of the evidence.

Question 12 (4 marks)

A student uses a displacement–time graph to report ‘wavelength = 0.40 s’. Evaluate and repair the answer, explaining what extra information would be needed to obtain wavelength.