i'm trying to finish up my online hw before the due date tonite at midnite. i have the rest perfect, just these three got me stumped.(adsbygoogle = window.adsbygoogle || []).push({});

7. [CJ6 4.P.038.] A cup of coffee is sitting on a table in an airplane that is flying at a constant altitude and a constant velocity. The coefficient of static friction between the cup and the table is 0.20. Suddenly, the plane accelerates, its altitude remaining constant. What is the maximum acceleration that the plane can have without the cup sliding backward on the table?

11. [CJ6 4.P.088.] A 75 kg water skier is being pulled by a horizontal force of 525 N and has an acceleration of 2.5 m/s2. Assuming that the total resistive force exerted on the skier by the water and the wind is constant, what force is needed to pull the skier at a constant velocity?

12. [CJ6 4.P.089.] A student presses a book between his hands, as the drawing indicates. The forces that he exerts on the front and back covers of the book are perpendicular to the book and are horizontal. The book weighs 29 N. The coefficient of static friction between his hands and the book is 0.31. To keep the book from falling, what is the magnitude of the minimum pressing force that each hand must exert?

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# Homework Help: 3 problems

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