Could you supply u with some answer choices please?
Answer:
Explanation:
Given
Electric Field 

velocity 
mass of electron 
Force on a charge Particle moving in Magnetic Field
![a=\frac{e\left [ \vec{E}+\left ( \vec{v}\times \vec{B}\right )\right ]}{m}](https://tex.z-dn.net/?f=a%3D%5Cfrac%7Be%5Cleft%20%5B%20%5Cvec%7BE%7D%2B%5Cleft%20%28%20%5Cvec%7Bv%7D%5Ctimes%20%5Cvec%7BB%7D%5Cright%20%29%5Cright%20%5D%7D%7Bm%7D)

Answer:
From the First Law of Motion
Vf = Vi + at
"It reaches a speed of 52m/s" meaning the Final speed Vf=52
a(acceleration)=10m/s²
t=4s
Applying the formula
52=Vi + 10(4)
Vi = 52-40
Vi = 12m/s
Answer:
I just answered a question like this. It should be B. An electromagnet :)
Explanation: