The second one is best. Gravity is an attractive force that acts between all objects, whether they're in contact or not.
Answer:
The answer is A)
Explanation:
An ionic compound is formed when one atom donates one or more electrons to one or more atoms of another element. Calcium has two valence electrons, which are donated to an atom of oxygen. So, an ionic compound is formed in the reaction involving one calcium atom with an oxygen atom.
Answer:
I think first one
Explanation:
Because his first law of motion was every object will remain at rest or uniform motion in a straight line
Answer:
y = 17,89 m
Explanation:
Let us fixate the reference point in top of the building, from where the watermelon is thrown down. We will assume also that the positive axis of our system points up. We describe the watermelon’s motion with the equation:

Clearing the equation so we isolate y we have that:

Making a substitution with the values from the statement we have:
]
So, this skyscraper is about 17,89 m tall; which is not very tall for a skyscraper but who am I to judge. 17,89 m is also the displacement of the watermelon from the point it was thrown down.
I hope everything was clear with my explanation. If I can help with anything else, just let me know. Have an awesome day :D
We have to convert Gm/s to m/s.
As 
Therefore the speed of light in vacuum,

Thus, the speed of light in m/s is 