Assuming the gravity to be in negative z-direction, a force `F=vxxA` is exerted on a particle in addition to the force of gravity where v is the velocity of the particle and A is a constant vector in positive x-direction. With what minimum speed a particle of mass m be projected so that it continues to move undeflected with constant velocity ?

Options

A. `-A/(mg) hat(j)`
B. `A/(mg) hat (j)`
C. `(mg)/A hat(j)`
D. `-(mg)/A hat(j)`

Answer

D

Explanation

`vec(F)=vec(V)xxvec(A)`
As `vec(F)=mg(-hatk)`
`vec(V)=((mg)/A)-hat(j)`