Answer;
- This statement about matter and its behavior is best classified as a Law.
-It is the Law of Universal Gravitation.
Explanation;
-The Law of Universal Gravitation states that every point mass attracts every other point mass in the universe by a force pointing in a straight line between the centers-of-mass of both points, and this force is proportional to the masses of the objects and inversely proportional to their separation.This attractive force always points inward, from one point to the other.
-The Law applies to all objects with masses, big or small. Two big objects can be considered as point-like masses, if the distance between them is very large compared to their sizes or if they are spherically symmetric.
The term you need to know is equilibrium. Technically it means that heat gained = heat lost. Normally in beginning chemistry classes the evidence for this condition is a stable temperature.
Answer:

Explanation:
The rotated angle is given by:

Since this is a quadratic equation it can be solved using:

Rewriting our equation:


Since
we discard the negative solution.

The velocity of the rock after 2s is 12.56 m/s.
The velocity of the rock at 25 m upwards is 14.68 m/s.
The velocity of the rock at 25 m downwards is -15.97 m/s.
The given parameters;
- <em>velocity of the rock, u = 20 m/s</em>
- <em>height of the rock, h = 20t - 1.8t²</em>
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The velocity of the rock after 2s is calculated as follows;

The velocity of the rock when the height is 25 m:
h = 20t - 1.8t²
25 = 20t - 1.8t²
1.8t² - 20t + 25 = 0
solve for the time of motion "t" using quadratic formula
a = 1.8, b = -20, c = 25

The value of t that will give 25 m upwards using the motion model is 1.43 s;
h = 20(1.43) - 1.86(1.43)² = 25 m
The velocity of the rock at 25 m upwards (t = 1.43 s) is calculated as follows;

The velocity of the rock at 25 m downwards (t = 9.67 s) is calculated as;

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Answer:
Work done is 50.4J.
Explanation:
The work
done by the student in lifting the book 1.2 meters vertically is


When the student begins to walk horizontally, the net force on the book is zero <em>(gravity is pulling it down, the student is lifting it up)</em>. Thus, although the student is displacing the book horizontally, but because no force is exerted on it, the work done is zero.