Why is gravitational force between two object usually unnoticeable

To notice that force, the objects have to have a big mass and be close to each others.

Generally in eveydays life, you don't notice this force since it is weak but that doesn't mean it does't exist.

If you go the space, you can notice this force since planets have big mass. If you get close to the gravitational field of a planet, you will feel a force that is pulling you toward the planet.

its 4 because 2 times 2 is 4, if you double the number two you get four

391.6 is the correct answer