Answer:
29.4 uN
Explanation:
The electric force between two charges can be calculated using Coulomb's Law. According to this law the force between two point charges is given as:

where k is a proportionality constant known as the Coulomb's law constant. Its value is
Nm²/C²
r = distance between charges = 70 cm = 0.7 m
q1 = q2 = 4nC =
C
The negative sign indicates that the charges are negative. In the formula we will only use the magnitude of the charges.
Using these values in the formula, we get:

Therefore, the magnitude of repulsive force between the given charges will be 29.4 uN
100 cm is 1 meter. So your answer would be 0.362 meters.
B. The apple from the bottom will hit the ground earlier. This is because an increase in height causes an increase in the time that the object will fall, and therefore will affect the final velocity of the falling object. Moreover, the reduction in velocity due to friction from the air should also be considered.
Answer:
The temperature and gravity both affects the density