Answer: relative motion between observer and the sound source.
Explanation: The Doppler effect states that when there is a relative motion between an observer and a sound source the frequency of sound perceived by the observer is different in frequency from the original from the source.
The mathematical back up for this claim is given below.
f' = (v+v') /(v-vs) × f
Where f' = observed frequency
v = speed of sound in air
v' = velocity of observer
vs = velocity of source
f = frequency of sound source.
From the formulae, it can be seen that a change in the value of the velocity of observer (v') and source (vs) produces different value of observed frequency (f').
Note, frequency of sound (f) is a constant.
Answer: A part of it heats up Earth's land and water equally.
The sun's energy help maintains Earth's energy budgets as the sunlight energy being absorbed by land and water from the sun. This results in the release on energy in the form of water vapors, gases like nitrogen dioxide, carbon dioxide, methane are again radiate back to the atmosphere. The water vapor chiefly is responsible for causing rain which is necessary for maintaining the life on earth. The other gases maintains the global temperatures.
Answer:
B. positive; negative.
Explanation:
From the viewpoint of Principle of Energy Conservation and Work-Energy Theorem, we notice that gravity represents a conservative force, associated with gravitational potential energy, whereas air resistance is a non-conservative force, associated with dissipated work. Therefore, the work done by gravity is positive and work done by air resistance is negative. Therefore, the correct answer is B.
Explanation: (Two liquids can have a very close boiling point) So it will be salt water. I think :C