When high power heater is used at homes all bulbs being used become dim. Why?

Answer

`2 m//s`

Explanation

Just before collision
Just after collision
By definition of `e : e = (v_(2) - v_(1))/(u_(1) - u_(2)) rArr (1)/(3) = (v + v)/(6 + 6) rArr v = 2 m//s`