2. (15 points) A dust speck (m = 1 ng) travels horizon- tally at speed u until it hits an ice cube of mass M = 1g
that is sitting at rest on a horizontal frictionless surface.
Having absorbed the dust speck, the ice cube proceeds
to travel horizontally with speed v = 3 ms-1.
What was the initial speed, u, of the dust speck?

Hints: (1) 1 ng = 10-9g. (2) See if you can figure out
why Newton would have gotten this question wrong.
What is the relativistic momentum? Do you need it for
the ice cube? How about the speck of dust?
U

grav forces affect all objects magnetic forces affect magnetic objects and electric currents

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.  

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.