2 blocks of masses 10kg nd 20 kg moving at speeds 10m/s nd 20m/s resp. in opp. directions, approach each other nd collide. the collisin is perfectly inelastic. find d thermal energy  developed in d process?

Kinetic energy lost = Thermal energy gained...

So now the 2 bodies collide.  When they collide inelastically we can calculate the velocity of the 2 bodies after collision

m1v1 + m2v2 = (m1+m2)v'  (remember the sign conventions it will eventually end up as 10*10-20*20=(20+10)v'. Now we've got the net velocity then we calculate the new kinetic energy as 1/2mv'2 which amounts upto 1500J. Subtarct this from the initial kinetic energies of the 2 bodies and we get the kinetic energy lost which gives thermal energy gained

the final answer is  4500J-1500J=3000J

no ans should be 3000J

see

initial momentum is  20 * 20 - 10 * 10 = 300kgm/sec

now conserving momentum

30 * V = 300

=> both will move together with 10m/sec

so energy lost = initial energy - final energy = 4500 - 1500 = 3000J