These are the characterstics of metal.
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The speed of the boy and his friend at the bottom of the slope is 16.52 m/s.
<h3>Their speed at the bottom</h3>
Apply the principle of conservation of energy,
E(up) - E(friction) = E(bottom)
mg sin(15) + ¹/₂(M + m)u² - μ(M + m)cos 15 = ¹/₂(M + m)v²
![v = \sqrt{2[\frac{mgd \ sin15 \ + \frac{1}{2}(M + m)u^2 \ -\mu (M + m)g cos\ 15 }{M + m}] }](https://tex.z-dn.net/?f=v%20%3D%20%5Csqrt%7B2%5B%5Cfrac%7Bmgd%20%5C%20sin15%20%5C%20%2B%20%5Cfrac%7B1%7D%7B2%7D%28M%20%2B%20m%29u%5E2%20%5C%20-%5Cmu%20%28M%20%2B%20m%29g%20cos%5C%2015%20%7D%7BM%20%2B%20m%7D%5D%20%7D)
where;
- u is the speed of the after 28 m
u = √2gh
u = √(2gL sin15)
u = √(2 x 9.8 x 28 x sin 15)
u = 11.92 m/s
![v = \sqrt{2[\frac{(30)(9.8)(70) \ sin15 \ + \frac{1}{2}(30 + 50)(11.92)^2 \ - 0.12 (30 + 50)9.8 cos\ 15 }{30 + 50}] }\\\\v = 16.52 \ m/s](https://tex.z-dn.net/?f=v%20%3D%20%5Csqrt%7B2%5B%5Cfrac%7B%2830%29%289.8%29%2870%29%20%5C%20sin15%20%5C%20%2B%20%5Cfrac%7B1%7D%7B2%7D%2830%20%2B%2050%29%2811.92%29%5E2%20%5C%20-%200.12%20%2830%20%2B%2050%299.8%20cos%5C%2015%20%7D%7B30%20%2B%2050%7D%5D%20%7D%5C%5C%5C%5Cv%20%3D%2016.52%20%5C%20m%2Fs)
Thus, the speed of the boy and his friend at the bottom of the slope is 16.52 m/s.
Learn more about speed here: brainly.com/question/6504879
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When red light and green lights shine on the same place on a piece of white paper, the spot appears to be Yellow in color. Complementary colors are always located directly across from each other on the graphic. For example cyan is located across from red, magenta across from green, and yellow across from blue. When primary color mix the produce secondary colors , for example a red light and a green light will combine to form a yellow color. The production of various colors of light by the mixing of the three primary colors of light is known as color addition.
Zeroth Law of Thermodynamics, which in turn will mean the heat will transfer between both of them up to the point where they are in thermodynamic equilibrium. So the answer is C.