A particle of mass m and charge q is thrown at a speed u against a uniform electric field E. How much distance will it travel before coming to momentary rest?

Answer

`m u^(2)//2 qE`

Explanation

From work energy theorem,
`F xx s` = Change in K.E. `= (1)/(2) m u^(2) - 0`
`qE xx s = (1)/(2) m u^(2)`
`s = (m u^(2))/(2qE)`