I’m pretty sure it’s C but it could be B. it is not A or D
<span>Theodore Roosevelt, 26th
President of the United States, was one of the most important
and effective environmental leaders in American history. Beginning in the 1880s and
culminating with his Presidency (1901-1909), his leadership of the emerging American
conservation movement was instrumental in preserving hundreds of millions of acres of natural
and historic treasures, including forests, wetlands, endangered species, native ruins, and “natural
wonders” like the Grand Canyon</span>
Answer:
In their House of Sound, Fran Scott and Greg Foot investigate how drums work.
Drums have been around for thousands of years and throughout history have often been involved in warfare -something they are reminded of as they play along to Mars from Holst’s The Planets suite.
Using confetti placed on a drum they use a slow motion camera to reveal how the confetti behaves like air molecules when the drum is struck.
The skin of the drum vibrates and makes the confetti dance.
As the air molecules vibrate against each other, sound waves are formed and the sound of the drums can be heard.
Fran explains that the pitch of a drum depends on how tight its skin is. If the skin is tight the drum makes a high note, if it is slack it makes a low note.
Greg points out the amount of air inside a drum also influences its pitch. The more air in a drum, the lower the note. The less air in a drum, the higher the note.
Volume depends on the size of the vibrations that are made.
Hit a drum hard and this makes big vibrations and a loud sound.
Hit a drum softly and the vibrations are smaller and the sound not as loud.
Together they make a drum kit out of things that can be found around the house, and Fran shows us how to make fun drums out of a plastic bowl and half a balloon.
This clip is from the series House of Sound.
