Question

A bomb at rest has mass 60 kg it explodeds and a fragment of 40 kg has kinetic energy 96 joule then kinetic energy of other fragment is-

Answer 1

ans is 192
momentum will remain conserved

Answer 2

Given :

Mass of bomb at rest , M = 60 kg .

It explodes and a fragment of 40 kg has kinetic energy 96 joule .

To Find :

The kinetic energy of 20 kg fragment .

Solution :

We know , kinetic energy is given by :

$K.E=\dfrac{mv^2}{2}$

Therefore ,

$v=\sqrt{\dfrac{2(K.E)}{m}}$

So , velocity of 40 kg fragment is :

$v=\sqrt{\dfrac{2\times 96}{40}}\\\\v=2.19\ m/s$

We know , since no external force is applied .

Therefore , momentum is conserved .

So , initial momentum = final momentum

$60\times 0=40\times 2.19 +20\times v\\\\v=-4.38\ m/s$

So , kinetic energy of 20 kg fragment is :

$K.E=\dfrac{20\times 4.38^2}{2}\\\\K.E=191.84\ J$

Therefore , kinetic energy of second fragment is 191.84 J .