11) A helicopter flying at 4000 feet begins its descent. It descends at a rate of 500 feet per minute. The function h(m) = 4000 - 500m represents the helicopter's altitude (height above ground) at m minutes
a) What is the altitude at 3 minutes?
b) What is the altitude at 6 minutes?
c) When is the altitude 3000 feet?
d) When is the altitude 500 feet?
e) When would the helicopter reach the ground?

this is an example of "committed" time.

committed time, as contracted time, takes need over essential and available time since it is seen as profitable work. it alludes to the time allotted to keep up a home and family. at the point when a man is commuting using committed time this individual may feel that the drive is an obligation to family, for example, strolling youngsters to class or driving a mate to work. contracted and committed time clients may feel that their commute could really compare to the commute of important or leisure time clients on the grounds that their commute is profitable work. in this manner, they might be more disposed to pick a mechanized method of movement.  

snell's law

refractve index = sin incidence / sin refraction