Answer: (a) The gravitational force on the object at the North Pole of Neptune is 51.7N
(b) The apparent weight of the object at Neptune's equator is 50.4N
Explanation: Please see the attachments below
Answer:
Decreased by a factor of 4.5
Explanation:
"We have Newton formula for attraction force between 2 objects with mass and a distance between them:

where
is the gravitational constant on Earth.
are the masses of the object and Earth itself. and R distance between, or the Earth radius.
So when R is tripled and mass is doubled, we have the following ratio of the new gravity over the old ones:




Since
and 

So gravity would have been decreased by a factor of 4.5
Answer:
You won't feel any change and will have no way to know that you've left the earth.
Explanation:
One of the formulations of the principle says that the properties of an inertial system under the effect of a gravitational field are the same as a non-inertial(accelerated) system. The inertial system under the effect of a gravitational field occurs when you are in the room on earth, and when the room is sent accelerating through space you have the non-inertial system. Both have the same properties, so it's impossible to tell the difference if you can't look outside.
There are a lot of same examples that you may have worked before, where the mass on a spring uses a classics when it comes to mechanics. So in this system, always put in your mind that there is an enormous quantum standard that one can use in the equation. It should be 2.10x10 raise to a negative sixth. J.