Answer:

Explanation:
Electric field strength= Force/unit charge
E= (kQq/r²)/q ₓ r
where r is the unit vector in the direction of unit charge
E= 
Answer:
A = 4.49
α = 57.72°
Explanation:
Knowing the magnitude of x & y of a vector we can determine the total magnitude of a vector.

The angle tangent can be used to determine the angle.

Answer:
when two object at different temperatures are in contact with each other.
Explanation:
I think the correct answer would be passbooks. It can be used to prove one's financial assets. It holds record of all bank transactions done on that particular account. Basically, all withdrawals and deposits are recorded there. Hope this helped.