There are four people in the car, the driver slams on the gas pedal and all the passengers heads hit the headrest behind them when the car accelerates forward. The reason the passengers' heads hit the headrest is because the passengers were at rest before the car started moving. Is this statement true or false?

True

Explanation:

Newton's first law (aka inertia) tells us that an object at rest tends to stay at rest and an object at motion tends to stay at motion. In this case, the passengers' heads were at rest, so they will tend to stay at rest when the car accelerates.

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)

snell's law

refractve index = sin incidence / sin refraction