Explanation:
Constellation: The complete sky has been divided in 88 different areas, in a way we have divided Earth in countries, not necessarily having same shapes and size. These 88 areas are known as constellations. These contains a lot of stars. When we join the brightest stars together we can imagine a shape out of them which is called as Asterism. Most of the people are unaware of this difference. Some of the famous constellations are Orion, Taurus, Gemini, Hydra, Ursa Major etc.
When an astronomer says that there is a comet is in the Orion, he means that a comet is in the boundaries of Orion constellation.
Tsunami and under water volcano
Mechanical
waves are oscillation of matter, they are important because they all
transfer energy from one place to another. There are 2 types of
mechanical waves. A transverse wave where the particles vibrate
perpendicular to the direction of energy travel and a longitudinal
wave where particle vibrations are parallel to the direction of the
energy transfer.
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Answer:

Explanation:
m = Mass of object = 
mg = Weight of object = 20 N
g = Acceleration due to gravity = 
v = Final velocity = 15 m/s
u = Initial velocity = 0
d = Distance moved by the object = 150 m
= Angle of slope = 
f = Force of friction
fd = Work done against friction
The force balance of the system is

The work done against friction is
.
The area under the acceleration time graph represents change in velocity
The graph is plotted with acceleration on the vertical axis and time on the horizontal axis. The area under such graph represents change in velocity