S99s(3) - Physics 4A FINAL EXAM Chapters 1 - 16 Spring 1999...

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Physics 4A FINAL EXAM Chapters 1 - 16 Spring 1999 1 Name:_________________________________________ Posting Code _____ _____ _____ Solve the following problems in the space provided. Use the back of the page if needed. Each problem is worth 10 points. You must show your work in a logical fashion starting with the correctly applied physical principles which are on the last page. Your score will be maximized if your work is easy to follow because partial credit will be awarded. 1. A child runs horizontally of the end of a diving board at a speed of 5.00m/s. The diving board is 1.20m above the water. Find (a)the time that the child is in the air and (b)the horizontal distance the child travels before hitting the water. x o = 0 y o = 1.20m x = ? y = 0 v ox = 5.00m/s v oy = 0 v x = 5.00m/s v y = ? a x = 0 a y = -9.80m/s 2 t = ? (a)Use the kinematic equation without the final speed for the y-direction, y = y o + v oy t + 1 2 a y t 2 0 = y o + 0 + 1 2 a y t 2 t = 2y o - a y = 2(1.20) - ( - 9.80) t = 0.495s . (b) Use the kinematic equation without the final speed for the x-direction, x = x o + v ox t + 1 2 a x t 2 x = 0 + v ox t + 0 x = (5.00)(0.495) x = 2.48m . 2. A 70.0kg skier heads down a 12.0˚ incline with an acceleration of 1.00m/s 2 . Find the coefficient of kinetic friction between the skis and the snow. The forces that act on the skier are the weight, normal force and friction. After drawing the free body diagram, apply the Second Law to each direction separately, Σ F x = ma x F g sin12˚ - F fr = ma F fr = F g sin12˚ - ma Σ F y = ma y F n - F g cos12˚ = 0 F n = F g cos12˚ . Using the definition of coefficient of friction,
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S99s(3) - Physics 4A FINAL EXAM Chapters 1 - 16 Spring 1999...

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