Well the US doesn't naturally have a lot of fossil fuels so we rely on other countries who do have fossil fuels. So if we aren't that friendly with Saudia Arabia (they have a bunch of oil) then they can hike up the prices or cut us off from their oil supply completely which would cripple the US severly. So with that being said, we NEED other countries, and the big question is when will they not NEED us. At any point in which they feel that they don't need us they can just cut us off, which would be bad.
Hope that helps :)
Take the derivative to find the velocity of the object:

The object stops when
:

so the answer is E.
Answer:
1800 m/
Explanation:
We know this because of Newton's first law,
, which shows us that the force on an object is equal to its mass times the acceleration it recieves. This means that taking our values of 900N and 0.5kg, and plugging them in,

This is honestly a little strange because the force applied and the acceleration seem ridiculous, and a little strange for an answer. Either the values are not meant to be nearly close to reality, or you made a typo.
the scientific study of natural forces such as light, sound, heat, electricity, pressure, etc.