Nootan Solutions Mass-Energy Equivalence ISC Class-12 Physics Ch-29 Nageen Prakashan Numericals. Step by step Solutions of Kumar and Mittal ISC Physics Class-12 Nageen Prakashan Numericals Questions. Visit official Website CISCE for detail information about ISC Board Class-12 Physics.

## Nootan Solutions Mass-Energy Equivalence ISC Class-12 Physics Ch-29

Board | ISC |

Class | 12 |

Subject | Physics |

Publication | Nageen Prakashan |

Writer | Kumar and Mittal |

Vol | 2nd |

Book Name | Nootan |

Chapter-29 | Mass-Energy Equivalence : Nuclear Binding Energy |

Topics | Solution of Numericals Questions |

Page-Number | 1029, 1030 |

#### Nootan Solutions Mass-Energy Equivalence ISC Class-12 Physics Ch-29

**mass and energy are inter-convertible**. So whenever you have mass, it means you have got lots of energy just sitting inside. How much energy? This is given in Einstein’s famous relation

**E=mc**

^{2}Where,

–> m is the mass in kilograms

–> c is the velocity of light in a vacuum c ≅ 3×10^{8} m/s

Which is 300 million in SI units. On squaring it, this number is huge. No wonder in saying that mass is concentrated energy.

For example, consider a little marble of 20-gram weight. Converting this 20g completely into energy contains we get the same amount of energy as is released in the explosion of a 500,000-ton hydrogen bomb. So why aren’t we afraid of marbles?

**Matter-Antimatter Annihilation :-**

This energy is really difficult to release. So if you have got a marble, there’s almost no way that you could release all that energy. The only way to convert all of that mass into energy is through matter-antimatter annihilation.

**Chemical Energy :-**

Water is a molecule formed by taking two hydrogen atoms and an oxygen atom thus making two bonds. The bond between oxygen and hydrogen, the bond between oxygen and the other hydrogen. These bonds cost energy, how much energy? 918 kilojoules per mol. Which implies that there are about 1.5× 10^{-18} joules of bond energy per molecule.

The change in mass is the energy, is given by

E = Δmc^{2}

Where,

- Δm is the change in mass
- c is the velocity of light

This mass defect is or the order 10^{10}, very minor number. Thus, not very considerate situation

**Neutron Star :-**

What about other processes that we could use to release all of this untouched energy? Well, neutron stars and black holes are probably our best bet for releasing the largest amount of this mass-energy other than matter-antimatter annihilation. It turns out that with a neutron star you can get relative releases of the energy of order 7 percent(7× 10^{-2}). So that’s 0.07 versus 0.00002, this is a huge amount of energy and with some types of rotating black holes, you can get it up to almost half, 42 percent.

Nootan Numerical Solutions Mass-Energy Equivalence ISC Class-12 Physics Ch-29

**Nageen Prakashan Numericals**

**Question 1:**

**Earth absorbs 10 ^{22 }joule energy every day from the sun. What will be the percentage increase in the earth’s mass (6.0 x 10^{22 }kg) due to this ?**

**Question 2:**

**Work out the energy ……………………… electron (9.1 x 10 ^{-31 }kg)**

**Question 3:**

**………………………**

**……………………..**

**………………………**

**Question 17:**

**Bombardment masses …………………………….. 931 MeV.**

**Question 18:**

**100 g of ………………………………. mol -1**

—: End of **Nootan Solutions Mass-Energy Equivalence** :–

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