A pont charge ` +q &` mass ` 100 gm` experiences a force of ` 100N` a a point at a distance ` 20 cm` from a long infinite uifromly charged wire , If it is relecased find its speed when it is at a distance ` 40` cm from wire .

Answer

` 20 sqrt(n2)`

Explanation

`E_A = (2k lambda) (.2) rArr (100)/Q = 10 K lambda`
` Kq lambda= 10` …(1)
` W_("fleld") = q int Edr` ….(2)

`W_("fleld") = Delta K = 1/2 mv^2` …(3)
From (2) and (3)
`1/2 mv^2 =q int_(0.2)^(0.4) (2 K lambda)/r dr = 2 q K lambda [ log _e r ]_(0.2)^(0.4)`
`1/2 mv^2 = 2 q K lambda ln 2` ...(4) .
`1/2 xx 0. 1 v^2 = 20 ln 2 rArr v = 20 sqrt l n^2`.