In quantum mechanics, a central concept is that both matter and <u>energy</u> are alternate forms of the same entity and therefore both exhibit dual characteristics of particles and of <u>waves</u>.
Matter can be defined as anything that has mass and is able to occupy space.
Thus, any physical object or substance that is found on Earth is typically composed of matter.
Similarly, energy is highly affected by the mass of a any physical object or substance just like matter,
Hence, both energy and matter are known to be made up of atoms and as a result of this fact, exhibit dual characteristics of particles and of waves.
A wave can be defined as a disturbance in a medium that progressively transports energy from a source location to another location without the transportation of matter.
In conclusion, this central concept makes it easier for us to better understand the behavior of tiny particles such as electrons.
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Answer:
Velocity, v = 0.239 m/s
Explanation:
Given that,
The distance between two consecutive nodes of a standing wave is 20.9 cm = 0.209 m
The hand generating the pulses moves up and down through a complete cycle 2.57 times every 4.47 s.
For a standing wave, the distance between two consecutive nodes is equal to half of the wavelength.

Frequency is number of cycles per unit time.

Now we can find the velocity of the wave.
Velocity = frequency × wavelength
v = 0.574 × 0.418
v = 0.239 m/s
So, the velocity of the wave is 0.239 m/s.
Answer:
1) move away from the windows.
When abrupt changes in pressure (produced by the hurricane) affect the windows, they can "explode" and be a serious danger for the people.
2) Go to the lowest level of the building.
Is safer than the upper levels because the lower levels suffer less from the strength of the hurricane (being closer to the ground increases the structural resistance), make sure that you have everything you may need in case of an emergency.
<span>Sea breeze can happen during hot summer days because of the
uneven heating rates of water and land.
The land surface heats up faster than the surface of the water during the
day. At this rate, the air above the
land grows warmer than the air atop the ocean. Warmer air is always lighter
than cooler air. As a consequence, warm air is pushed upward causing it to
rise. With this, warmer air rises over the land. As warm air rises over the
land, cooler air over the ocean flows over the land surface to change or
replace the rising warm air.</span>
Constructive interference in performance halls and the elimination of echoes are reasons why choir concerts better in performance halls than in gymnasiums.
<h3>What is constructive interference?</h3>
Constructive interference is a phenomenon which occurs when two waves travelling in same direction and which are in phase add up together to produce a wave of greater amplitude.
Constructive interference occurs in performance halls while destructive interference occurs in gymnasiums.
Also in performance halls, echoes are minimized due to the padded walls and the curtains while echoes which disturb choir concerts occur in gymnasiums.
Therefore, choir concerts better in performance halls than in gymnasiums because of constructive interference in performance halls and the elimination of echoes.
Learn more about constructive interference and echoes at: https://brainly.in/question/2378717