8.2 Speed of Sound

1. When there is a lightning strike you might see the lightning a few seconds before you hear the thunder. Why does this happen?

• Sound travels faster than light
• The rain slows down the sound
• Light travels faster than sound
• The Light doesn't have to travel at all

2. Which of these are NOT units of speed

• metres per second
• miles per hour
• Kilometres per minute
• miliseconds per metre

3. Which is the correct equation to find the time (an object has taken to travel a certain distance)?

• s = d/t
• t = d/s
• t = d x s
• t = s / d

4. If sound travels at a speed of 340 m/s how far will the sound have travelled in 5 seconds? s=d/t

• 3400 m
• 1700 s
• 38 m
• 1700 m

5. In water, sound can travel 1000 m in 0.6 s. Calculate the speed of sound in water to 2 dp. s=d/t

• 1666.67 m/s
• 1666.6 m/s
• 600 m/s
• 0.0006 m/s

6. Which statement best describes how the particles are arranged in a solid?

• The particles are tightly packed together with very little space between them
• There are wide spaces between the particles and they can move around freely
• The particles are close together but can slide past each other

9. Gethin and Llinos want to measure the speed of sound through the air. They have a stop-clock and they stand near a wall and time how long it takes to hear the echo of a clap. Which TWO ways can they best improve the accuracy of their measurement?

• Stand as far away from the wall as possible to get a longer time to hear the echo
• Stand as close to the wall as possible to hear the echo better
• Repeat the experiment three times
• Use a whistle instead of clapping

10. Seren is on holiday in the Swiss alps and tries yodelling from the top of a mountain. The sound reflects off a nearby mountain and Seren hears her echo 8 seconds later. How long did it take the sound to reach the nearby mountain? t=d/s

• 8 seconds
• 340 seconds
• 4 seconds
• 16 seconds

11. If the speed of sound through the air was 340 m/s, how far away is the nearby mountain? Use the following equation to help: d=sxt

• 1360 m
• 2720 m
• 42.5 m
• 85 m

12. Which best describes echolocation?

• The high pitched clicks and whistles given out by dolphins
• Used by some mammals to navigate.The animal emits sound and detects the echoes as they bounce back
• Used by bats when they listen carefully to the sounds made by insects, to hunt for food