Two blocks of masses `10kg and 20kg` moving at speeds of `10ms^(-1) and 20ms^(-1)` respectively in opposite direction approach each other and colide .If the collision is completely inelastic , find the thermal energy developed in the process

Answer

C

Explanation

`m_(1) = 10kg,V_(1) = 10m//s`
`m_(2) = 20kg,V_(2) = 20m//s`
Here `m_(2)V_(2) - m_(1)V_(1) = (m_(1) + m_(2))V`
`rArr 20 xx 20 - 10 xx 10 = (10 + 20)V`
`rArr 400 - 100 = 30V`
rArr 300 = 30V`
rArr V =10m//s`
Initial kinetic energy
`= (1)/(2) m_(1)u_(1)^(2)+ (1)/(2)m_(2)u_(2)^(2)`
`= (1)/(2) xx 10 xx (10)^(2) + (1)/(2) xx 20 xx (20)^(2)`
` = 500 + 4000 = 4500`
Final kinetic energy `= (1)/(2) (m_(1) +m_(2))V^(2)`
`= (1)/(2) (10+20)(10)^(2)`
`= ((30)/(2)) xx 100 = 1500`
THe total change on K.E.`= 4500 - 1500= 3000J`
The thermal enrgy devloped in the process `= 3000J`