Answer:
A. 20 N
Explanation:
weight of book is 2×10=20N
The speed of the man and the chair after the book is thrown is 0.2 m/s.
The given parameters:
- <em>mass of the book, m₁ = 2.1 kg</em>
- <em>speed of the book, u₁ = 7.2 m/s</em>
- <em>mass of the man, M = 70 kg</em>
- <em>mass of the book, m = 9.2 kg</em>
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The total mass of the man and the book is calculated as follows;
m₂ = 70 kg + 9.2 kg
m₂ = 79.2 kg
The speed of the man and the chair after the book is thrown is determined by applying the principle of conservation of linear momentum;

Thus, the speed of the man and the chair after the book is thrown is 0.2 m/s.
Learn more about conservation of linear momentum here: brainly.com/question/7538238
Answer:D) in a straight line.
Hey
Newton's first law says that if an object is at rest it will stay at rest. But if it is moving it will continue moving in a straight line if there is no external force. If there where no gravity the object that you throw will keep going in a straight line according to Newton's first law.
Answer:1.28v/k
Explanation:
Thermoelectric power is the same as Seebeck coefficient.
So the formula is S =Vemf/Th - Tl
= 12.8/310-300
S= 12.8/10
=1.28V/T
So we want to know how does the speed of a shallow water wave varies. If the wavelength is large enough in comparison to the depth of the water, meaning the wavelength is 20 times longer than the depth of water, the speed of a shallow water wave is the square root of gravity times water depth or: v=√(g*d), where v is speed of the wave, g=9.81 m/s^2 and d is water depth.