Answer:
Almost all machines require energy to offset the effects of gravity, friction, and air/wind resistance. Thus, no machine can continually operate at 100 percent efficiency.
Answer:
C. Mantle
Explanation:
The Mantle is a thick layer of solid and partially melted rock
Answer: RATE ME AND MAKE ME BRAININESS AND THANK ME
Explanation:Sound waves are pressure waves that travel through Earth's crust, water bodies, and atmosphere. Natural sound frequencies specify the frequency attributes of sound waves that will efficiently induce vibration in a body (e.g., the tympanic membrane of the ear) or that naturally result from the vibration of that body.
Sound waves can potentiate or cancel in accord with the principle of superposition and whether they are in phase or out of phase with each other. Waves of all forms can undergo constructive or destructive interference. Sound waves also exhibit Doppler shifts—an apparent change in frequency due to relative motion between the source of sound emission and the receiving point. When sound waves move toward an observer the Doppler effect shifts observed frequencies higher. When sound waves move away from an observer the Doppler effect shifted observed frequencies lower. The Doppler effect is commonly and easily observed in the passage of planes, trains, and automobiles.
The speed of propagation of a sound wave is dependent upon the density of the medium of transmission. Weather conditions (e.g., temperature , pressure, humidity , etc.) and certain geophysical and topographical features (e.g., mountains or hills) can obstruct sound transmission. The alteration of sound waves by commonly encountered meteorological conditions is generally negligible except when the sound waves propagate over long distances or emanate from a high frequency source. In the extreme cases, atmospheric conditions can bend or alter sound wave transmission.
Answer:
True
Explanation:
There are 9 carbon atoms, 8 hydrogen atoms and 4 oxygen atoms, therefore the subscript 9 belongs.
