A particle (mass - 5 g. charge 30 mC) moves in a region of space where the electric field is uniform and is given by Ex 4.8 N/C, Ey-E. 0. If the velocity of the particle att-O is given by v,-40 m/s V, v-0, what is the speed of the particle at t3 s?

speed is Vf = 46.4 m / s

Explanation:

This is an exercise where we must use Newton's second law to find the acceleration of the particle due to the electric field and the kinematic equations to find the velocity in the given time.

F = ma

a = F / m

F = E q

a = q E / m

a = 30 10⁻³ 4.8 / 5 10⁻³

a = 28.8 m/s²

Note that the force is repulsive because the charge is positive and the field is also positive.

Having the acceleration of the body we can look for speed, knowing that the initial speed is Vo = - 40 m / s

Vf = Vo + a t

VF = - 40 + 28.8 3

Vf = - 40 + 86.4

Vf = 46.4 m / s

I am not sure of your notation. If the speed is Vo = 40 m / s

Vf = 126.4 m / s