Science 7 · Unit 6: Earth physics · Cambridge Lower Secondary Science Stage 7

Questions

1. 1. What is a reflected sound wave called?

   • a vibration
   • an echo
   • a note
   • a sound
   Check

2. 2. Which of these will reflect sound best?

   • a flat wall
   • tall grass
   • a large tree
   • a sandy beach
   Check

3. 3. Arun walks through a tunnel and hears each footstep twice. Why?

   • His shoes make two sounds.
   • Someone is walking behind him.
   • The sound travels in a vacuum.
   • The sound reflects off the hard walls, so he hears an echo.
   Check

4. 4. Where will Arun hear more echoes when he plays the guitar?

   • in a tunnel
   • in a field
   Check

5. 5. Echo loudness: A 52 dB, B 65 dB, C 38 dB, D 44 dB. Which surface gives the loudest echo?

   • D
   • C
   • A
   • B
   Check

6. 6. Echo loudness: A 52 dB, B 65 dB, C 38 dB, D 44 dB. Which surface gives the quietest echo?

   • B
   • D
   • C
   • A
   Check

7. 7. Echo loudness: A 52 dB, B 65 dB, C 38 dB, D 44 dB. Which surface would be best for a music recording room?

   • C
   • B
   • A
   • D
   Check

8. 8. What kind of surface absorbs sound and makes fewer echoes?

   • hard and flat, like tiles
   • smooth and shiny, like glass
   • hard and bare, like a concrete floor
   • soft and uneven, like curtains or carpet
   Check

9. 9. Sofia stands 85 m from a tall cliff and bangs a drum. How far does the sound travel before she hears the echo?

   • 85 m
   • 170 m
   • 42.5 m
   • 340 m
   Check

10. 10. Sound travels at 340 m/s. Sofia stands 85 m from a cliff and bangs a drum. How long until she hears the echo?

    • 0.5 s
    • 0.25 s
    • 4 s
    • 2 s
    Check

11. 11. How can a submarine detect a large rock in the dark?

    • It waits until it hits the rock.
    • It uses a magnet.
    • It sends out a sound and listens for the echo off the rock.
    • It shines a light.
    Check

12. 12. How can the submarine tell how far away the rock is?

    • by how loud the engine is
    • by the colour of the water
    • by how cold the water is
    • by timing how long the echo takes to come back
    Check

13. 13. Bats use echoes to find insects. How does a bat work out where an insect is?

    • by smelling the insect
    • from the time the echo takes to come back, and the direction it comes from
    • from how warm the insect is
    • from the colour of the insect
    Check

14. 14. A boat sends a sound down through the water. The echo comes back from the solid ground. What can the boat find out?

    • how salty the water is
    • the depth of the water under the boat
    • the speed of the wind
    • the temperature of the water
    Check

15. 15. Which of these uses echoes to make an image?

    • a photograph taken with a camera
    • a drawing made with a pencil
    • a shadow on a wall
    • a scan of an unborn baby inside its mother
    Check

16. 16. Why are theatres designed without large flat surfaces?

    • so the sound is louder
    • so there are no echoes, and the audience can hear the voices clearly
    • so the stage is easier to see
    • so more people can sit down
    Check