Answer:
The speed of the electron is
.
Explanation:
Given that,
The magnitude of electric field, 
The magnitude of magnetic field, B = 0.516 T
Both the magnetic and electric fields are acting on the moving electron. Then, the magnitude of electric field and magnetic field is balanced such that :

or

So, the speed of the electron is
. Hence, this is the required solution.
Since momentum is a vector quantity, take any direction as positive and other as negative. Answer won't change.
Answer:2800000j
Explanation:
For us to know the kinetic energy of the vehicle,
Where m is the mass
And v is the velocity
Then, K.E=1/2mv^2
While, K.E=1/2×3500×40^2
Therefore, our answer will now be
K.E=2800000j
If one of two interacting charges is doubled, the force between the charges will double.
Explanation:
The force between two charges is given by Coulomb's law

K=constant= 9 x 10⁹ N m²/C²
q1= charge on first particle
q2= charge on second particle
r= distance between the two charges
Now if the first charge is doubled,
we get 
F'= 2 F
Thus the force gets doubled.