Answer:
D. gravity
Explanation:
Gravity keeps the atmosphere from escaping into space.
<h2>
Answer:50
</h2>
Explanation:
Let
be the airspeed.
Let
be the cross wind speed.
We know that,ground speed is the vector sum of airspeed and cross wind speed and airspeed is perpendicular to cross wind speed.
If
and
are two perpendicular vectors,the resultant vector has the magnitude 
Given,

So,the ground speed is 
it will move the object if you apply force, because of that it will stay the same with newton's law.
Compound; consists of atoms of two or more different elements bound together,can be broken down into a simpler type of matter (elements) by chemical means (but not by physical means) has properties that are different from its component elements, and always contains the same ratio of its component atoms.Mixtures; Note that a mixture:consists of two or more different elements and/or compounds physically intermingled, can be separated into its components by physical means, and often retains many of the properties of its components.