I believe it should be B.
Here’s one desctiption:
When the balloon has been rubbed enough times to gain a sufficient negative charge, it will be attracted to the wall. Although the wall should normally have a neutral charge, the charges within it can rearrange so that a positively charged area attracts the negatively charged balloon
Hopefully it’s right!
The answers B because your doing m/s
Answer:

Explanation:
To find the force we proceed by defining the variables we have,

The charge on one of the balls is defined under the equation,



Due to the height we need to calculate the potential energy at the height of 115m,

The kinetic energy would be given by

From the law of conservation we equate the two equations




In this way we now calculate the strength of the particle



Answer:
The efficiency of the engine is 40 %
Explanation:
Given;
input energy, = 2500 J
output energy, = 1000 J
The efficiency of the engine is given as;
Efficiency = output energy / input energy
Efficiency = 1000 / 2500
Efficiency = 0.4
Efficiency(%) = 0.4 x 100%
Efficiency = 40 %
Therefore, the efficiency of the engine is 40 %
Answer:
0.5
Explanation:
The energy of a charged capacitor is given by
where
is the charge on it and
is its capacitance. The capacitance is defined, geometrically, as

where
is a constant that is determined by the material between the plates,
is the area of the plates and
is the distance between them. It is then that the capacitance is linearly inversely proportional to the separation distance; as the distance increases, the capacitance reduces.
Because it is linear, when the separation distance is doubled, other factors remaining constant, the capacitance is halved. Because the capacitance is halved, the energy is halved.
Let's see the mathematics.
Initial capacitance,
at initial separation, 

If separation is doubled, separation becomes
. Then the capacitance becomes




Initial energy, 
Final energy, 

Hence, 