Unformatted text preview: Dr. Galeazzi PHY205 Test #2 March 7, 2010 Signature: ___________________________ I.D. number: _________________________ Name:_______________________________ 1 You must do the first problem which consists of five multiple choice questions. Then you must do three of the four long problems numbered 25. Clearly cross out the page and the numbered box of the problem omitted. Do not write in the other boxes. If you do all the problems, only problems 14 will be graded. Each problem is worth 25 points for a total of 100 points. TO GET CREDIT IN PROBLEMS 2 5 YOU MUST SHOW GOOD WORK. 2 3 4 CHECK DISCUSSION SECTION ATTENDED: [ ] Dr. Nepomechie 2O, 9:30 10:20 a.m. [ ] Dr. Voss 2Q, 12:30 1:20 p.m. [ ] Dr. Voss 2R, 2:00 2:50 p.m. [ ] Dr. Huffenberger 2S, 3:30 4:20 p.m. [ ] Dr. Galeazzi 4P, 11:00 11:50 a.m. TOTAL 5 THE EQUATION SHEET IS PROVIDED ON THE LAST PAGE WHICH YOU CAN TEAR OFF. 1 Dr. Galeazzi [1.] PHY205 Test #2 March 7, 2010 This problem has five multiple choice questions. Circle the best answer in each case. . What is the / [1A.] The drag force on a parachute jumper of mass m is given by maximum speed the jumper can reach? [a] / [b] [c] / [d] / [e] [1B.] A toy train with mass m moves at constant speed on a circular track of radius R. If the train completes one lap in a time T, what is the magnitude of the net force acting on the train? [a] [b] [c] [d] 0 [e] 4 [1C.] A ball with mass m is hanging from a chain with mass m/2, which, in turn, is connected to the ceiling. What are the magnitudes of the tension at the top and bottom of the chain respectively? [a] , [b] , [c] , [d] , [e] , [1D.] A cart with mass m is initially moving on a horizontal plane at speed v. A force which increases with distance as is then applied to the cart until, after a distance L, its speed doubles. If the coefficient of kinetic friction of the cart is , find the net work on the cart from where the force is first applied, to the distance L. [a] [b] [c] [d] [e] none of the above [1E.] If you are in the seat of a ferris wheel and, at the top of the wheel, you feel weightless, which of the following statements must be true: [a] The wheel must be in uniform circular motion; [b] The net force on your body is zero; [c] The gravitational force on your body is zero; [d] The seat you are in is accelerating; [e] You acceleration is zero; 2 Dr. Galeazzi PHY205 Test #2 March 7, 2010 3 Dr. Galeazzi PHY205 Test #2 March 7, 2010 [2.] A horizontal spring with coefficient k is initially compressed a length L and "loaded" with a block of mass m, which is not attached to the spring. Spring and block are sitting on a horizontal surface which is frictionless in the area of the spring.
[a] Calculate the work done by the spring once it is released. [b] Find the speed of the block right when it is released by the spring. . How [c] After the mass in released, it enters a rough region with coefficient of kinetic friction far will the block travel in this region before it stops? Write your results in terms of k, L, m, each answer. , and g. Remember to check the dimensions/units for  4 Dr. Galeazzi PHY205 Test #2 March 7, 2010 5 Dr. Galeazzi PHY205 Test #2 March 7, 2010 [3.] An amusement park ride consists of small cars of mass m attached to steel cables of length L (cable 1). The cables have negligible mass and are attached to a spinning post (see figure). A second horizontal cable of negligible mass (cable 2) connects the cars to the post and, when fully stretched, limits the maximum angle of the top cable to a value . of the ride to fully stretch the cable 2? [a] What is the minimum angular velocity (HINT: the minimum angular velocity is the one for which cable 2 is fully stretched, but has zero tension) [b] If the ride is spinning with angular velocity , what is the tension in cable 2? in cable 1? [c] For the same angular velocity of part [b], what is the tension Write your results in terms of m, L, , each answer. , and g. Remember to check the dimensions/units for  6 Dr. Galeazzi PHY205 Test #2 March 7, 2010 7 Dr. Galeazzi PHY205 Test #2 5 is given by sin , March 7, 2010 [4.] The position of a particle with mass with [a] [b] [c] 4 and . Find the force acting on the particle as a function of time, . Find the force acting on the particle as a function of the particle's position Find the net work done on the particle between 0 and . . Write your results in terms of the quantities (and units) given.  8 Dr. Galeazzi PHY205 Test #2 March 7, 2010 9 Dr. Galeazzi PHY205 Test #2 March 7, 2010 [5.] Block A in the figure has mass and coefficient of static friction with respect to the incline's surface. The masses of both the cable and the pulley are negligible. [a] What is the minimum value of mass so that the two masses do not move? so that the two masses do not move? [b] What is the maximum value of mass [c] If the two blocks are initially at the same height, and the cable is cut, which block will reach the surface of the table underneath with the higher speed? Explain. Write your results in terms of each answer. , , , and . Remember to check the dimensions/units for  10 Dr. Galeazzi PHY205 Test #2 March 7, 2010 11 Dr. Galeazzi PHY205 Test #2
EQUATION SHEET (Make sure to start all problems from these equations only) March 7, 2010 Vectors: Linear motion: 2D: , ; ; ; tan ; ; ; cos , ; sin . Relative velocity: ; Newton's Laws: Examples of forces: Work: 0 ; 0; ; ; friction:  , 0  , ; ; ; WorkEnergy Theorem: Circular motion: Uniform circular motion: ;  ;  ; ; ; 2 ; ; 12 ...
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 Galeazzi
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