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
63,200 J.
45,000 J.
30,400 J.
23,400 J.
OPTION 2: 45,OOO J
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
v1=10m/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
m1v1+m2v2/m1+m2=0
solve for v2 and substitue it in the next equation u will get the answer