Roads often have to be repaved because they crack over time. sometimes this cracking is due to the fact that the roads (as well as other objects) have a tendency to expand when heated and contract when cooled. thermal expansion and contraction are examples of
a.
physical and chemical changes.
b.
physical changes.
c.
chemical changes.
d.
neither physical nor chemical changes.

Nacidified solution was electrolyzed using copper electrodes. a constant current of 1.18 a caused the anode to lose 0.584 g after 1.52 ✕ 103 s. given that the charge of an electron is 1.6022 ✕ 10−19 c, calculate avogadro's number. assume that copper is oxidized to cu2+ ions.

Four point charges each having charge q are located at the corners of a square having sides of length a. find symbolic expressions for the following. (a) the total electric potential at the center of the square due to the four charges (use any variable or symbol stated above along with the following as necessary: ke.) vtotal= (b) the work required to bring a fifth charge p from infinity to the center of the square (use any variable or symbol stated above along with the following as necessary: w=

Which planet do you think would be easiest for humans to colonize some day?