A(n) 1090 N man stands in the middle of
a frozen pond of radius 6.09 m. He is un-
able to get to the other side because of a
lack of friction between his shoes and the
ice. To overcome this difficulty, he throws his
1.05 kg physics textbook horizontally toward
the north shore, at a speed of 4.53 m/s.
How long does it take him to reach the
south shore?

Question

A(n) 1090 N man stands in the middle of
a frozen pond of radius 6.09 m. He is un-
able to get to the other side because of a
lack of friction between his shoes and the
ice. To overcome this difficulty, he throws his
1.05 kg physics textbook horizontally toward
the north shore, at a speed of 4.53 m/s.
How long does it take him to reach the
south shore?

anonymous · Answer

This is a momentum problem.
Once the man throws the book, the speed he gets multiplied by his mass will be equal to the mass of the boss multiplied by 4.53.

So if we set up the momentum equation:
(1090/9.81)(his velocity) = (1.05)(4.53)

The reason I divided 1090 by 9.81 is because 1090 is the force he is exerting on the ground (his weight). It is his mass multiplied by gravity, so I divided by the acceleration due  to gravity.

Doing the math, we get roughly 0.043 m/s.

From here, it's just basic physics. The man is standing still, so he has no initial acceleration.
So we have:
distance = velocity * time
time = distance/velocity
distance = 6.09 m
velocity = 0.043 m/s

So:
time = ~142 s.