The impulse required to decrease the speed of the boat is equal to the variation of momentum of the boat:

where
m=225 kg is the mass of the boat

is the variation of velocity of the boat
By substituting the numbers into the first equation, we find the impulse:

and the negative sign means the direction of the impulse is against the direction of motion of the boat.
The orbital radius is: 
Explanation:
The problem is asking to find the radius of the orbit of a satellite around a planet, given the orbital speed of the satellite.
For a satellite in orbit around a planet, the gravitational force provides the required centripetal force to keep it in circular motion, therefore we can write:

where
G is the gravitational constant
M is the mass of the planet
m is the mass of the satellite
r is the radius of the orbit
v is the speed of the satellite
Re-arranging the equation, we find:

Learn more about circular motion:
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Answer:
14 billion years
Explanation:
The Hubble – Lemaître law, previously called the Hubble law, is a law of physics that states that the redshift of a galaxy is proportional to the distance it is, which is the same as, the further one galaxy is found from another, more quickly it seems to move away from it.
The Hubble constant is the value that measures the rate at which the expansion speed of the Universe varies with distance, and is one of the fundamental parameters of the Universe and allows, in particular, to determine the age of the Universe as we will see.