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# Monthly Archives: December 2011

## Happy New Year

Ask Physics wishes all its members a very Happy New Year

Is the energy required to break a sample of string proportional to the length of string or is the energy requirednto break the sting constant?

Ans

The energy required to break a string depends on the stress known as tensile failure stress.It is not related to the length of the string .for more knowledge ref. Mohr’s theory

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## A question from Maths (for Members and Visitors)

“Find the relationship between L(the length of the shape L-shape)and S(the number of small squares in the L-shape)P(the perimeter of the L-shape)T(the total number of match sticks). Will 600 match sticks be enough to build a L-shape with sides of 100 squares?”

## What is impact parameter?

Impact parameter is the perpendicular distance between the velocity vectors of two objects (considered to take part in a collision) when they are at infinite distance (at such a distance that there is no interaction between the two particles)

In Rutherford’s alpha scattering experiment, the gold nucleus is at rest and therefore, in this case

Impact parameter is the perpendicular distance between the gold nucleus and the the direction of the velocity vector of alpha particle when the alpha particle is at infinite distance (i.e; the force of interaction between the gold nucleus and the alpha particle is negligibly small)

## Calculating Unknown Mass

Ricardo ,of mass 80 kg , and carmelita , who is lighter , are enjoing lake merced at dusk in a 30 kg canoe . When the canoe is at rest in the placid water ,they exchange seats which are 3m apart and symmetrically located with respect to canoe center . Ricardo notices that canoe moves 40cm relative to submerged log during the exchange and calculate carmelitas mass ,which she has not told him . What is it? (Piyush posted)

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