Sample Final Exam Physics 131 Spring 2009 Final exam on Thu May 14 from 1:30 to 3:30 pm 1) Mark >>> A <<< AS YOUR ANSWER TO THE FIRST QUESTION 2) A jet lands at 62 m/s, applying the brakes 3 s after landing. Find the acceleration needed to stop the jet within 600 m of landing. A) -10.33 m/s2 B) 4.64 m/s2 C) 3.20 m/s2 D) -3.20 m/s2 E) -4.64 m/s2 3) A 200-gram ball moves with a velocity of -35.0 m/s. What is its kinetic energy? A) B) C) D) E) -1.2 x 102 J 1.2 x 102 J -1.2 x 105 J 1.2 x 105 J 2.4 x 102 J 4) An astronaut applies a force of 555 N to an asteroid, and it accelerates at 1.5 m/s2. What is the asteroid’s mass? A) 71 kg B) 135 kg C) 370 kg D) 3500 kg E) 833 kg 5) Two blocks, initially at rest, are released from the top of a building. One falls straight down while the other slides down a smooth ramp. If all friction is ignored, which one is moving faster when it reaches the bottom? A) B) C) D) E) The block that went straight down. The block that went down the ramp. They both will have the same speed. Depends on time. None of the above. 1 6) A ball is thrown horizontally from a 20-m-high building with a speed of 5.0 m/s. How far from the base of the building does the ball hit the ground? A) 10 m B) 20 m C) 8 m D) 16 m E) 4 m 7) A bead of mass m = 8.00 kg is released from point A with an initial speed of 10 m/s and slides on the frictionless track shown in the figure. The height of A is ha = 6.70 m and that of B is hb = 3.20 m. Determine the bead's speed at point B. A) B) C) D) E) 84.3 m/s 169 m/s 13.0 m/s 71.2 m/s 22.0 m/s 8) An automobile of mass 2500 kg moving at 20 m/s is braked suddenly with a constant braking force of 9000 N. How far does the car travel before stopping? A) B) C) D) E) 55.6 m 90.7 m 135 m 180 m 72.5 m 9) If an object is moving at constant velocity, which of the following statements is correct? A) Since the object is moving, there must be a constant force that keeps pushing on it. B) There is no net force acting on the object. C) No force is needed to keep the object’s velocity constant because the object contains a natural force of motion. D) The object will keep moving at constant velocity as long as its acceleration is greater than zero. E) None of the above. 2 10) A horizontal force of 750 N is needed to overcome the force of static friction between a level floor and a 250-kg crate. What is the coefficient of static friction? A) B) C) D) E) 3.0 0.15 0.28 0.31 0.46 11) A block is launched up an inclined plane. After going up the plane, it slides back down to its starting position. The coefficient of friction between the block and the plane is 0.3. The speed of the block when it reaches the starting position on the trip down: A) B) C) D) E) Is the same as the launching speed Is less than the launching speed Is more than the launching speed Cannot be compared to the launch speed with the information given Not enough info given 12) Jane pushes a box 6 m by applying a 25 N force at an angle 25 degrees above the horizontal. What work does she do? A) B) C) D) E) 16 J 66 J 106 J 136 J 150 J 13) A student reading his physics book on a lake dock notices that the distance between two incoming wave crests is about 4 m, and then measures the time of arrival between wave crests to be 2 s. What is the approximate speed of the waves? A) B) C) D) E) 1 m/s 2 m/s 6 m/s 8 m/s 4 m/s 14) A strong man is compressing a lightweight spring between two weights. One weight has a mass of 2.3 kg, the other a mass of 5.3 kg. He is holding the weights stationary, but then he loses his grip and the weights fly off in opposite directions. The lighter of the two is shot out at a speed of 6.0 m/s. What is the speed of the heavier weight? A) B) C) D) E) 2.6 m/s 13 m/s 3.4 m/s 9.2 m/s 1.3 m/s 3 15) A block of mass 5.00 kg rests on a horizontal surface where the coefficient of kinetic friction between the two is 0.200. A string attached to the block is pulled horizontally, resulting in a 2.00m/s2 acceleration by the block. Find the tension in the string. A) B) C) D) E) 0.200 N 19.8 N 29.8 N 12.0 N 9.80 N 16) The impulse imparted by the wall to the 10-kg cart is A) B) C) D) E) -30 kg m/s -20 kg m/s -10 kg m/s 20 kg m/s 30 kg m/s 17) When a certain 2 m long wire is held rigidly at both ends and set into vibration, the velocity of waves on the wire is 200 m/s. Consider standing waves on the wire. What is the wavelength of the longest wavelength standing wave on the wire? A) B) C) D) E) 2m 1m 0.5 m 8m 4m 18) [Refer to the previous problem.] What is the frequency of the second harmonic standing wave? A) B) C) D) E) 25 Hz 50 Hz 100 Hz 75 Hz 200 Hz 4 19) A Martian lander is approaching the surface. It is slowing its decent by firing its rocket motor. Which is the correct free-body diagram for the lander? 20) Consider a large truck carrying a heavy load, such as steel beams. A significant hazard for the driver is that the load may slide forward, crushing the cab, if the truck stops suddenly in an accident or even in braking. Assume, for example, that a 12000 kg load sits on the flat bed of a 20000 kg truck moving at 15.0 m/s. Assume the load is not tied down to the truck and has a coefficient of static friction of 0.600 with the truck bed. Calculate the minimum stopping distance for which the load will not slide forward relative to the truck. A) B) C) D) E) 24.0 m 10.0 m 55.0 m 9.5 m 19.0 m 21) A tube that is open at both ends supports a standing wave with harmonics at 300 Hz and 400 Hz, with no harmonics in between. What is the fundamental frequency of this tube? A) B) C) D) E) 100 Hz 200 Hz 150 Hz 50 Hz 300 Hz 5

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