There's no such thing as one balanced force or one unbalanced force.
If ALL of the forces in a GROUP of forces acting on the same object
all add up to zero, then we say that the GROUP of forces is balanced.
If they don't, then the GROUP of forces is unbalanced.
Two or more forces can be balanced or unbalanced.
One force can't.
2.5e+20 grams is the right answer
20 cm = bright
40 cm = dim
The longer the wire the bigger the resistance
After the collision, the momentum didn't change, so the total momentum in x and y are the same as the initial.
The x component was calculated by subtracting the initial momentum (total) minus the momentum of the first ball after the collision
In the y component, as at the beginning, the total momentum was 0 in this axis, the sum of both the first and struck ball has to be the same in opposite directions. In other words, both have the same magnitude but in opposite directions

This is for both balls after the collision, but one goes in a positive and the other in a negative direction.
Virtual images are produced when rays of a light (after reflection or refraction) appear to meet a a certain point. While real images are produced when rays of a light (after reflection or refraction) meet at some point.