Answer:
<u><em>First Reaction:</em></u>
=> 
<u><em>Second Reaction:</em></u>
=> 
<u><em>Combined Reaction:</em></u>
=> 
A real image is smaller than the object
Steel materials produce less vibrations whilst less dense and more malleable parts produce more vibrations, e.g. the wooden part of the coaster itself.
Decreases by a factor of 4. Electric force is inversely proportional to distance squared