To test how sound travels through solids, a simple phone can be made by tying a plastic cup at each end of a string (about 30 feet). Two people, one person at each end of the string, can transmit sound to one another by speaking into the cup at his or her end. The sound travels through the string in waves and reaches the other person's cup. Think about the sound can be changed in this investigation,
Which statements are true about how sounds heard through the cup phone can be changed?
To make the pitch of the sounds higher, students should use thicker string
Shortening the string between the cups will increase the volume
Students who wrap their hands around their cups will hear sound better than those who do not
To increase the volume on the opposite end of the string, ask a third person to pinch the string in the middle.
Lengthening the string between the cups will increase the volume.
Sound travels better through string than in air because sound travels best through solids.
A string with more tension carries sound better than one with less tension
Waves
gical advancement

so here is the information for current research:

-nrel's geothermal analysts, scientists, and engineers perform a full range of research from developing advanced methods of locating and accessing geothermal resources to exploring innovative technologies to extract and produce clean energy from the heat of the earth

and here is the information for the technology of geothermal energy:

-it's clean and sustainable

-resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma

-almost everywhere, the shallow ground or upper 10 feet of the earth's surface maintains a nearly constant temperature between 50° and 60°f (10° and 16°c)

-geothermal heat pumps can tap into this resource to heat and cool buildings

-a geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building

-in the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system

-in the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger

-the heat removed from the indoor air during the summer can also be used to provide a free source of hot water

force tends to be low and long diustance masses are high