Doppler Effect is required to solve the problem. The Doppler effect is the change in the perceived frequency of any wave movement when the emitter, or focus of waves, and the receiver, or observer, move relative to each other. The general formula of observed frequency, due to Doppler's effect is as follows,

= Frequency observed by observer
v = Velocity of Sound
= Velocity of observer
= Velocity of source
= Frequency of source
PART A) Replacing our values we have that,



PART B) Here the same procedure is performed but this time repeated in the opposite direction.



-- If the force is applied in the <em>same direction</em> as the object is moving, then the object's momentum in that direction will <em>increase</em>.
-- If the force is applied in the direction <em>OPPOSITE </em>to the way the object is moving, then the object's momentum will <em>decrease</em>.
-- In either case, the CHANGE in the object's momentum will be
(strength of the force) x (length of time the force is applied) .
This quantity is also called "impulse".
Answer: Option (c) is the correct answer.
Explanation:
An elastic object is defined as the object that is able to retain its shape when a force is applied on it.
For example, when we pull a rubber band then it stretches and when we withdraw the force applied on it then it retain its shape.
As we know that potential energy is the energy obtained by an object due to its position.
So, when we stretch a rubber band then it will have elastic potential energy as position of the rubber band is changing and since, it will retain it shape hence it has elastic potential energy.
Thus, we can conclude that a stretched rubber band has elastic potential energy.
The array of colors observed when viewing films of soap are caused by the interference, and from the reflections of light from two nearby surfaces (outer surface and inner surface). Among the choices, the closest answer would be B. reflection, refraction, and interference.
Answer:
D. Hydrogen combines with oxygen to form water.
Explanation:
Hydrogen combining with oxygen to form water is a typical example of chemical reaction.
During a chemical reaction, atoms of elements are rearranged. Most chemical reactions obey the law of conservation of mass which states that "matter is neither created nor destroyed in a chemical reaction but atoms are simply rearranged".
The other choices given are nuclear reactions. In such reactions, atoms are not rearranged but are simply destroyed and made in the process.