170 EXPERIMENTAL GENERAL SCIENCE 



Practical Exercises 



1. How does clapping the hands or firing a cannon produce sound? 



2. Recall the playing of a band at a distance. Do different sounds 

 have different rates of speed, or do they travel with the same speed in the 

 same medium? 



3. How far away is the lightning if the thunder is heard three seconds 

 after the flash is seen? 



4. A steamer five miles from shore is seen to blow her whistle. How 

 long before the sound would be heard by a person on shore? 



6. Whore would you expect conversation to be more easily heard, 

 in deep mines or on mountain tops? Why? 



6. How far away is the reflecting surface if an echo is heard half a 

 second after the original sound? 



7. How long will it take for an echo to reach you if the reflecting 

 surface is 1100 feet away? 



8. Could one hear better by placing the small end of a megaphone 

 to the ear? Why? 



9. Why are echoes more likely to occur in a large than in a small 

 room? 



10. Why do empty rooms often produce echoes when the same rooms 

 furnished do not? 



11. When a sea-shell is held to the ear, a roaring sound, which some 

 people believe to be the roaring of the sea, can be heard. What causes 

 the sound? 



