A railway carriage of mass 9000kg moving with a speed of `36kmh^(-1)` collides with a stationary carriage of the same mass. After the collision, the two get coupled and move together. What is this common speed ? What type of collision is this?

Explanation

`m_(1)=9000kg,u_(1)=36km//h=10m//s`
`m_(2)=9000kg, u_(2)=0,v=v_(1)=v_(2)=?`
By conservation of momentum
`m_(1)u_(1)+m_(2)u_(2)=(m_(1)+m_(2))v`
`:.v=5m//s`
Total K.E before collision `=1/2 m_(1)u_(1)^(2)+1/2m_(2)u_(2)^(2)`
`=45000J`
Total K.E. after collision `=1/2(m_(1)+m_(2))v^(2)=225000J`
As totla K.E. after collision `gt` Total K.E. before collision