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Explain the following phenomenon on the basis of Newton's Laws of Motion

a) Falling of building during an earthquake
b) Shattering of car windows due to a bomb blast
c) Cell phone breaks into pieces on falling from a table
d) Finger cuts while suddenly pulling the thread of an air borne kite
e) Guitarists' finger gets injured while sliding it on a guitar string


1- During an earthquake, ​buildings are suddenly forced to move very quickly that it suffers damage. Newton's second law of motion F=(mv-mu) / t  or F=ma is applied here.
During an earthquake, the speed at which both the ground and building are moving will reach some maximum. The more quickly they reach this maximum, the greater their acceleration.
2-  ​​The glasses of a car windows shatter due to a bomb blast because as the bomb blasts it compresses the air surrounding it to large pressure and when this wave hits the glass surface with a high speed it applies a great force on the glasses and breaks them. Here, Newton's second law (F=dP/dt=mv-mu/t ) is applied.  
3- ​When a cell phone falls on the ground from the table with a speed. Its momentum becomes zero in a very short time interval. So, then applying ​Newton's second law (F=dP/dt=mv-mu/t ), a great force is exerted on it. Thus, it breaks.
4- While suddenly pulling the thread, the momentum is reduced to zero in a very short interval of time. ​So, then applying ​Newton's second law (F=dP/dt=mv-mu/t ), a great force is exerted on finger and it hurts.
5-Same as (4). Also the string is very thin having less cross sectional area. Thus, P=F/A, a high pressure is applied and guitarist's finger gets injured.
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u need to tell which Law of motion is applied here

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A)   Inertia of rest.  Foundation is at rest and top of the building vibrates.

During the Earth quake the foundation of the building is held by the soil. But the top end of the building is free to vibrate.  So it vibrates laterally (in horizontal direction).   If the shear stress on the building due to the quake is more than what the building can withstand (breaking stress), then building will break.
    If the building bends at the top in such a way that the line of center of mass of building falls outside the base of the building, then it collapses.

b)  2nd law.   F = m a    and    F = P . A         F = change in momentum / time duration
An Instant after a blast very high pressure regions regions are created in the air.  Due to the extremely high pressure waves and vibrations in the air the glass windows of cars or houses break.

c)   F = change in momentum / time duration    2nd law

Cell phone or any brittle object breaks into pieces after falling from a height.  It is due to the impact on the object during the collision.  The momentum of the object is a small amount.  But the impact is during very little time like 0.1 sec or less.  So the force exerted by the floor on the object is very high.  This force divided by area exposed during impact is more than the breaking stress of the object. So it breaks.

d)      3rd law.  Every action has opposite equal reaction.   (reaction force of thread causes)
  stress = force / area  .  the surface area of contact between the thread and finger is very small.  The pull of the kite requires considerable force.  SO the stress is very very high and more than the tolerance limit for the skin. That is why the skin is penetrated by the stress on the skin.  The contact force (friction force) is the cause.  If we hold the thread loosely then the fingers do not get cut.

e)    third law -  reaction force from the strings causes injury.

The guitarists fingers get cut if he slides fingers along the string.  This is also due to the frictional force (and applied force ) between the fingers and the string.  Due to the surface are a of string being very small and the object being dry and tight,  the friction force is very high.  SO stress is high.   It is like a needle or sharp knife penetrating the skin.

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so which law of motion r we applying????????
i will write... wait a moment
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