Properties of wavesIB MYP Physics: Subtopic test

1. 1
   A cork floats on the surface of a pond in Kerala. A stone is dropped into the pond and ripples spread outwards. As the ripples pass, the cork bobs up and down but stays in about the same place.

   (a)

   What does the motion of the cork show about waves?

   [1 mark]

   • AWaves transfer energy without transferring matter
   • BWaves carry water particles from the stone to the edge of the pond
   • CWaves transfer matter but not energy
   • DWaves stop transferring energy when they reach an object

   (b)

   The distance between neighbouring crests of the ripples is 4 cm. What is the name of this quantity?

   [1 mark]

   • AAmplitude
   • BFrequency
   • CWavelength
   • DPeriod

   (c)

   State how the direction of the vibrations differs between transverse and longitudinal waves, and give one example of each type.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A wave machine in a swimming pool in Singapore produces regular water waves with a frequency of 0.50 Hz and a wavelength of 3.0 m.

   (a)

   What is the period of the waves?

   [1 mark]

   • A0.50 s
   • B2.0 s
   • C1.5 s
   • D3.0 s

   (b)

   What is the speed of the waves?

   [1 mark]

   • A6.0 m/s
   • B3.5 m/s
   • C0.17 m/s
   • D1.5 m/s

   (c)

   The wave speed in the pool stays at 1.5 m/s. The frequency of the wave machine is increased to 1.0 Hz. Calculate the new wavelength.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student uses a ripple tank to measure the speed of water waves. A motor makes a straight bar dip into the water 8.0 times each second, which produces a train of waves. The student holds a ruler beside the pattern and measures a distance of 12.5 cm across 5 complete wavelengths.

   (a)

   Calculate the wavelength and the speed of the water waves.

   [3 marks]

   (b)

   Explain why the student measured across 5 wavelengths instead of 1, and suggest one improvement that would make the results more reliable.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A coastal town in Indonesia has a tsunami warning system. Sensors on the seabed detect the long water waves produced by an earthquake and sirens warn the town. In the deep ocean the waves travel at 200 m/s and have a wavelength of 100 km (100 000 m). The town is 1200 km from the earthquake.

   (a)

   Calculate the frequency of the waves, the period of the waves and the time the first wave takes to reach the town.

   [6 marks]

   (b)

   Discuss the benefits and drawbacks of spending public money on tsunami warning systems for coastal towns, and evaluate whether governments should do so.

   [6 marks]

   Total for question 4: 12 marks

End of questions