Transverse and longitudinal waves

Answer Key - Grade 11 Science Worksheet

Circle the best answer, or write your answer on the line.

1. 1.

   A seismograph records the S-wave 10 s after the P-wave. In this rock, P-waves travel 6.0 km/s and S-waves 3.5 km/s. How far away is the quake, Ari?

   84 km
2. 2.

   A seismograph records the S-wave 25 s after the P-wave. In this rock, P-waves travel 6.0 km/s and S-waves 3.5 km/s. How far away is the quake, Bo?

   210 km
3. 3.

   Jun shakes the same rope at twice the frequency, with the tension unchanged. What happens to the wave speed and the wavelength?

   • The speed and the wavelength both halve
   • The speed stays the same and the wavelength halves
   • The speed doubles and the wavelength stays the same
   • The speed doubles and the wavelength halves
4. 4.

   The tension in a rope is made 4 times as large. Wave speed goes with the square root of tension. The shaking frequency stays the same. What happens to the wavelength, Kira?

   • It stays the same
   • It quadruples
   • It halves
   • It doubles
5. 5.

   A wave passes from a light rope into a heavy rope. The frequency stays the same. What happens to the wavelength, Luz?

   • It stays the same, since the same hand shakes both ropes
   • It gets longer, since a heavy rope carries waves farther
   • It gets shorter, since the wave travels more slowly on the heavy rope
   • It gets shorter, since the frequency rises in the heavy rope
6. 6.

   A microphone records the pressure peaks (compressions) of a sound arriving every 2.5 ms. What is the frequency, Milo?

   • 2.5 Hz
   • 40 Hz
   • 400 Hz
   • 4,000 Hz
7. 7.

   That 400 Hz sound travels in 20 °C air at 343.3 m/s. What is its wavelength, Noah?

   • About 1.2 m
   • About 0.43 m
   • About 0.86 m
8. 8.

   Ren asks why sound cannot be polarized by a filter that polarizes light. Which explanation is right?

   • Sound is longitudinal, so it has no sideways direction of vibration to filter
   • Sound waves are already polarized in the air they travel through
   • Sound waves have no frequency for a filter to act on
   • Sound waves are far too slow to be able to pass through a filter designed to work on light
9. 9.

   A wave travels right along a rope. At one instant, point P is at the top of a crest. What is the velocity of P at that instant, Tala?

   • Down, since it is about to fall
   • Right, at the speed of the wave
   • Zero: it is momentarily at rest at its highest point
   • Up, since the point has just been lifted by the crest approaching it from the left
10. 10.

    As a wave passes, where is a point on the rope moving fastest, Zee?

    • Everywhere the same, since the wave speed is constant
    • At the rest position, passing through the middle
    • At the trough
    • At the crest, where the rope is displaced furthest from its rest position