A 100 kg mass is blown apart into a 90.0 kg piece and a 10.0 kg piece. After the blast, the two masses are moving apart with a relative velocity of 100 m/s. The velocity of the 10.0 kg mass after the explosion is 90.0 m/s. The total kinetic energy of the two masses after the explosion is

  • Option 1)

    63,200 J.

  • Option 2)

    45,000 J.

  • Option 3)

    30,400 J.

  • Option 4)

    23,400 J.


Answers (2)


Centre of mass remains at rest. So its speed is zero.

(m1v1+m2v2) / (m1+m2) = 0

m1v1 + m2v2 = 0

m1 =90kg

m2= 10kg

v2= 90m/s

v2- v1= 100m/s


Total KE = 1/2 x m1x v1^2 +1/2x m2x v2^2

By substituting the values

Total KE = 45000J


take it the reverse way.. like two mases colliding to form one mass and after collision the complete mass is at rest. so


solve for v2 and substitue it in the next equation u will get the answer


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