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Applications on Newtons Second Law

“A particle of mass 2m is on a plane inclined at an angle 36.86 to the horizontal. The particle is attached to one end of a light inextensible string. The string runs parallel to a line of greatest slope of the plane, passes over a smooth pulley at the top of the plane and then hangs vertically carrying a particle of mass 3m at its other end. The system is released from rest with a single taut. Find the acceleration of each particle and tension in the string when the particles are moving freely, given that the plane is smooth.”

 

Asked Gina

The Physics of Accidents

Accidents

Why are road accident at high speeds very much worse than accidents at low speeds?

Asked Muneem.

Answer:

As you might have studied, greater the speed, greater is the momentum. When an accidents occurs, the greater momentum involved can cause greater damage.

Please ferer to the links below for details

1. http://outreach.phas.ubc.ca/phys420/p420_96/danny/danweb.htm

2. http://ffden-2.phys.uaf.edu/211_fall2002.web.dir/ben_townsend/PhysicsofCarCollisions.htm

 

Reaction problem

NINE FIVE RUPEE COINS ARE PUT ON TOP OF EACH OTHER ON A TABLE.EACH COIN HAS A MASS m kg .THE REACTION OF THE FIFTH COIN(COUNTED FROM BOTTOM)ON SIXTH COIN IS.
Asked Alvy
Answer:-)
4mg as there are invited4 coins above the 5th coin from bottom.

The Physics of Carpet Cleaning!

Why when a hanging carpet is beaten with a stick, the dust particles start coming out of it?

Please explain to me, in a simple language.

Asked Osho Garg

Answer:

This is due to the inertia of rest of the dust particles.

When the mat is beaten suddenly with a stick, the mat moves forward, but the dust tends to remain at the same position on account of the inertia of rest. When the mat/ carpet moves, the dust particles lose support and they fall down

Newton’s Third Law of Motion and some doubts

Newton’s Third Law of Motion states that

“Every action has equal and opposite reaction”

In other words,

“Whenever a body exerts a force on another body, the second body exerts an equal and opposite force on the first body”

 Osho Garg asks:

“if a person is sitting on a chair both the chair and person exert force against it so we called that ” there is always an equal and opposite reaction ” but for example a elephant of mass 584 kg sit on a chair, the chair will broke.  So what we called for this . Please explain.

 

Answer:

When an elephant “sits” on a chair, it breaks because it cannot give the “equal reaction” and  it “yields” to it.

Therefore, here the force is doing “work”.

More discussions are welcome

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