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S06s(3) - Physics 204A FINAL EXAM Chapters 1 14 Spring 2006...

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Physics 204A FINAL EXAM Chapters 1 - 14 Spring 2006 1 Name:__________________________________ 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. The equations you need are on the equation sheet. Your score will be maximized if your work is easy to follow because partial credit will be awarded. 1. A soccer ball is kick with a speed of 18.0m/s at a 30.0˚ angle above the horizontal. Find (a)the time it is in the air and (b)the distance it travels before it hits the ground. (a)Using the kinematic equation along the y-axis, y = y o + v oy t + 1 2 a y t 2 . Putting in the things that are zero and solving for t, 0 = 0 + v oy t + 1 2 a y t 2 " t = # 2 v oy a y = # 2 v o sin \$ a y . Plugging in the numbers, t = " 2(18.0)sin30.0˚ " 9.80 # t = 1.84 s . (b)Using the kinematic equation along the x-axis, x = x o + v ox t + 1 2 a x t 2 = v ox t = v o t cos " . Plugging in the numbers, x = (18.0)(1.84)cos30.0˚ " x = 28.6 m . 2. A gardener pushes a 7.00kg lawn mower at the constant speed of 0.800m/s across level ground by exerting a force of 60.0N directed along the handle, which makes a 50.0˚ angle with the horizontal. Find the size of (a)the normal force and (b)the frictional force on the mower. Applying the Second Law for each direction remembering that the constant velocity means no acceleration, " F x = ma x # F p cos \$ % F fr = 0 and " F y = ma y # F n \$ F p sin % \$ F g = 0 . Soling the y-equation for the normal force and the x-equation for the frictional force, F fr = F p cos " and F n = F p sin " + F g . Plugging in the numbers, F fr = 60.0cos50.0˚ " F fr = 38.6 N and F n = 60.0sin50.0˚ + (7.00)(9.80) " F n = 115 N . x y v o θ x o = 0 y o = 0 x = ? y = 0 v ox = v o cos θ v oy = v o sin θ v x = v ox v y = ? a x = 0 a y = -9.80m/s 2 t = ? t = ? F p F g F n F fr x y F p F g F n F fr θ

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Physics 204A FINAL EXAM Chapters 1 - 14 Spring 2006 2 3. The golf club shown at the right is 1.00m long. The head has a mass of 700g and the shaft has a mass of 200g. The center of mass is 85.0cm below the top of the shaft. At the bottom of the swing, the club head is moving at 9.00m/s in circular motion about the top of the shaft. Find the vertical component of the force that the shaft exerts on the head at this instant.
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