Freddy drives 4 miles east to his friends house. He then travels 9 more miles east to the supermarket. Finally on his way back home he runs out of gas 6 miles after leaving the supermarket. (A) What distance did Freddy travel? (B) What was Freddy’s total displacement?

Amichelson interferometer operating at a 600 nm wavelength has a 3.02-cm-long glass cell in one arm. to begin, the air is pumped out of the cell and mirror m2 is adjusted to produce a bright spot at the center of the interference pattern. then a valve is opened and air is slowly admitted into the cell. the index of refraction of air at 1.00 atm pressure is 1.00028.how many bright-dark-bright fringe shifts are observed as the cell fills with air?