Fall 2008 Quiz #6 PHYS-218Sec Date: Oct. 20, 2008Print NamesThis is your GROUP quiz. Be sure to write all of your assumptions out in words.Draw sketch(es) and derive your equations before coming to an answer. Do NOTwrite the answer alone. Write the answer in a separate paper.Give the answers with two or three significant figures.1. A box with weight w = 770 N is on a rough surface, inclined at an angle of 37 degrees. The boxis kept from sliding down (in equilibrium) by means of an external force F . The other forces actingon the box are the normal and friction forces, denoted by n and f . A force diagram, showing thefour forces that act on the box, is shown in the figure. The magnitude of f is 210 N. What is themagnitude of the external force F ?2. A box with weight 55 N is on a rough horizontal surface. An external force F is appliedhorizontally to the box. A normal force and a friction force are also present, denoted by n and f .A force diagram, showing the four forces that act on the box, is shown in the figure. When forceF equals 2.0 N, the box is in motion at constant velocity. When force F equals 2.6 N, what is theacceleration of the box?3. A system comprising blocks, a light frictionless pulley, a frictionless incline, and connectingropes is shown. The 9-kg block accelerates downward when the system is released from rest. Whatis the acceleration of the system?4. An 8.0-kg block is released from rest, v1= 0 m/s, on a rough incline. The block moves a distanceof 1.6-m down the incline, in a time interval of 0.80 s, and acquires a velocity of v2= 4.0 m/s.(a) What is the work done by the weight of the object?(b) What is the average rate at which the block gains kinetic energy during the 0.80 s timeinterval?5. An object with m = 2.5 kg, sliding on a rough surface, has a speed of 1.2 m/s when it makescontact with a spring. The block comes to a momentary halt when the compression of the springis 5.0 cm. The work done by the friction, from the instant the block makes contact with the springuntil is comes to a momentary halt, is -0.50 J.(a) What is the coefficient of friction?(b) What is the spring constant k?(c) After compressing the spring, the block moves away from it. What is the speed of the blockupon separation from the
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