Answer:
The man moves across the ice with a speed of 0.345m/s.
Explanation:
From the conservation of linear momentum, we have that the total linear momentum before the book throw is equal to the total linear momentum just after it. Since the initial velocity of the system is zero (so the initial momentum is zero), we have that:

Where
is the mass of the man,
is the mass of the book, and
and
are their velocities. Plugging in the given values, we can compute the speed of the man (ignoring the negative sign, because we care about the magnitude, not the direction):

In words, the resulting speed of the man is 0.345m/s.
Answer:
d = 13 miles
Explanation:
Lets say the position of court house is origin in this case
her office is located at 4 miles west and 4 miles south of court house
so here we have coordinate of the office with respect to court house is given as

now the position of her home is located at 1 miles east and 8 miles north of the court house
so the coordinates of her home is given as

now the change in the position is given as the distance between office and home



Explanation:
Attachments of the solution are below.
Answer:
The unit of speed is m/s.
Answer: Dark matter.
Explanation: Hope it helps :)