Answer:
Vf = - 20 m/s ( -ve sign shows that the particle is moving opposite to positive x- direction).
Explanation:
Given:
Vi = 20 m/s, m= 10 mg =1 × 10⁻⁵ kg, q= -4.0 × 10⁻⁶ C , E= 20 N/C. t= 5.0 s
first to find Electric Force
F= Eq = 20 × -4.0 10⁻⁶ C = - 8 × 10⁻⁵ N (-ve sign shows that the field will push the particle opposite to positive x- direction)
We also have F=ma
⇒ a = F/m = - 8 × 10⁻⁵ N / 10 × 10⁻⁵ kg = -8 m/s² ( -ve sign shows that the particle is accelerated opposite to positive x- direction)
Now according the first equation of Motion.
Vf = Vi + at
Vf = 20 m/s + -8 m/s² × 5 s
Vf= -20 m/s ( -ve sign shows that the particle is moving opposite to positive x- direction)
