(only answer if you know the answer or I'll report) Solve it w the steps tysm​

 v_f = 20 m / s

Explanation:

For this exercise let's use the relationship between momentum and moment

        I = Δp

        F t = m v_f - m v₀

as the body starts from rest v₀ = 0

        F t = m v_f

        v_f =

let's calculate

        v_f = 4 2 / 0.4

         v_f = 20 m / s

the higher the current the higher the mag field around it the higher the influence on the compass

massxgravity x heght=weightxheight= pe

4900=490xh

h=10