Workers pushing a 180 kg trunk across a level floor encounter a 10 m long region where the floor becomes increasingly rough; the coefficient of kinetic friction increases from μ0 = .17 to .79 according to the expression ( μk = μ0 + ax^2 ) where a = 0.00062 m^-2, and x is the distance in meters from the beginning of the rough region.
how much work does it take to push the trunk at constant speed across the region?

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.

365.25 earth days are in the year of a light year

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explanation: