Answer:
Increases 
Explanation:
The expression for the capacitance is as follows as;

Here, C is the capacitance,  is the permittivity of free space, A is the area and d is the distance between the parallel plate capacitor.
 is the permittivity of free space, A is the area and d is the distance between the parallel plate capacitor.
It can be concluded from the above expression, the capacitance is inversely proportional to the distance. According to the given problem, the capacitor is disconnected from the battery and the distance between the plates is increased. Then, the capacitance of the given capacitor will decrease in this case.
The expression for the energy stored in the parallel plate capacitor is as follows;

Here, E is the energy stored in the capacitor, C is the capacitance and Q is the charge.
Energy stored in the given capacitor is inversely proportional to the capacitor. The charge on the capacitor is constant. In the given problem, as the distance between the parallel plates is being separated, the energy stored in this capacitor increases.
Therefore, the option (c) is correct.
 
        
             
        
        
        
Once the car is on top of the hill it contains potential energy witch means it is storing enough energy to slide the hill until acted on. Once the car moves and slides down the hill it creates kinetic energy witch means it's in motion. The car then turns the kinetic energy into mechanical energy witch means it's working. I'm not sure if that helped but good luck!
 
        
             
        
        
        
Answer:
Explanation:
mg = kx
x = mg/k
x = 30(80)(9.8)/2.8e7 = 0.00084 m  ≈ 1 mm