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# Monthly Archives: September 2012

## A Complicated problem from force and motion

A particle is at rest. A force F is continuously pushing it forward at all velocities it attains till infinite time say till n seconds where n tends to infinity find the final relation for velocity, force, energy etc .”

Originally shared by Shatendra Sharma Professor at Jawaharlal Nehru University

Do you know the solution? Post them as comment to this post.

## How protons became closer during Big bang process?

I know that strong nuclear force is a short-ranged force. So, I would like to know how protons became closer during Big bang process. Is it because of very high temperature and pressure during this ?

(thatoekhant)

In nuclear fusion the nucleons (protons and neutrons come closer because of their high energies. When they come closer to each other in the order of distances of fermi (10^-15 m) nuclear force – the strongest force in nature, comes into play

… Awaiting responses

## Black Holes and Space

Is it possible that matter falling into a black hole would emerge in some form of elementary particles or energy in some other point in space or even time (space/time)?

I thought that matter couldn’t be destroyed just transformed into energy or some other form of matter.

Articles or theories on what happens to matter falling into a black hole say that it just falls out of existence.  That doesn’t make sense.

(Posted by Victor )

Responses:
“I have few knowledge about this subject, even though I think that ordinary matter when enters into blackholes may convert into darkmatter, ie energy associated with ordinary matter escapes & the matter will convert into darkmatter. From the origin of our universe this process may take place & this may be the reason that the amount of darkmatter is greater than that of ordinary matter.Here matter is not destroyed because total matter(including dark matter & visible matter ) remains constant.” … Anitha Anand (Student at university college,TVM)

## Problems from Relativity

A spacecraft starts from earth moving at constant speed to planet A which is 20 lighthour away from Earth. It takes 25 hour (according to an earth observer) for a spacecraft
to reach this planet. Assuming that clocks are synchronized at the beginning of the
journey, compare the time elapsed in the spacecraft frame for this one-way journey with
the time elapsed as measured by an earth-based clock?

Posted by Mahmoud

## How does the atmosphere rotate with the Earth?

How does the atmosphere rotate with the Earth? (Asked George)

## Equilibrium – Numerical Problem

SOLID HEMISPHERE OF RADII R EACH, are placed in contact with each other with each other with their flat faces on a rough horizontal surface. A sphere of mass m and radius R is placed symmetrically on top of them. The normal reaction between the top sphere and any hemisphere assuming the system to be in state equilibrium is

## Physics vector problem

A dog in an open field runs 12.0 east and then 26.0 in a direction 51° west of north.

a)In what direction must the dog then run to end up 11.0 south of her original starting point?

b)How far must the dog then run to end up 11.0 south of her original starting point?

Posted by Ami

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