Answer:
Rust is a compound. What makes iron rust is its reaction with oxygen and moisture in the air.
It expands due to heat and makes it easier to open the jar.<span />
Potential energy increases as speed decreases. Kinetic increases when speed increases.
Answer:

Explanation:
The charge on one object, 
The distance between the charges, r = 0.22 m
The force between the charges, F = 4,550 N
Let q₂ is the charge on the other sphere. The electrostatic force between two charges is given by the formula as follows :

So, the charge on the other sphere is
.
My educated guess : 21.2 deg