The correct option is D The horizontal and vertical components of acceleration are ax=0, ay=qEm
Since, there is no force acting on the mass in the x direction, Fx=0
Now, since the electric field acts downwards, the force acting on the particle in the y direction, Fy=qE
∴ Using Fy=may
So, option (b) is the correct answer.
Now considering the second equation of motion, x=uxt+12axt2
∵ ux=v and ax=0
Similarily, for y=uyt+12ayt2
∵ uy=0 and ay=qEm
So, option (d) is the correct answer.
We, have from (1), t=xv
Substituting t=xv in (2), we get
So, option (c) is the correct answer.
Now, kinetic energy KE is,
where, vx=v and vy=ayt=qEmt
So, option (a) is the incorrect answer.
Hence, options (b) , (c) and (d) are the correct answers.