A charged particle of mass m and charge q is projected on a rough horizontal XY plane. Both electric and magnetic fields are given by `vec(E)=-10hat(k)N//C` and magnetic field `vec(B)=-5vec(k)` tesla are present in the region. The particle enters into the magnetic field at `(4,0,0)m` with a velocity `50vec(j) m//sec`. The particle starts into a curved path on the plane. If coefficietn of friction `mu=(1)/(3)` between particle and plane, then `(qE=2mg,g=10m//s^(2))`.
Total distance covered by the particle is

Options

A. `100m`
B. `125m`
C. `200m`
D. `50m`

Answer

B

Explanation

`a=(mu(mg+qE))/(m),v(dv)/(ds)=(mu(mg+qE))/(m)=g`
`int ds=int(vdv)/(g)impliess=(50xx50)/(2xx10)=125m`