12. A 20-kg crate is suspended from a fixed beam by two vertical ropes. What is the tension in each rope? A) 10 N B) 40 N C) 100 N D) 200 N E) 390 N

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1 Name: Date: 1. The surface of a lake has an area of 15.5 km 2. What is the area of the lake in m 2? A) m 2 B) m 2 C) m 2 D) m 2 E) m 2 2. A certain physical quantity, R, is calculated using the formula: R = 4a 2 (b c) where a, b, and c are distances. What is the SI unit for R? A) cm B) cm 2 C) m D) m 2 E) m 3 3. Which one of the following quantities is a vector quantity? A) the age of the earth B) the mass of a football C) the earth's pull on your body D) the temperature of an iron bar E) the number of people attending a baseball game 4. Three vectors A, B, and C add together to yield zero: A + B + C = 0. The vectors A and C point in opposite directions and their magnitudes are related by the expression: A = 2C. Which one of the following conclusions is correct? A) A and B have equal magnitudes and point in opposite directions. B) B and C have equal magnitudes and point in the same direction. C) B and C have equal magnitudes and point in opposite directions. D) A and B point in the same direction, but A has twice the magnitude of B. E) B and C point in the same direction, but C has twice the magnitude of B. Page 1

2 5. City A lies 30 km directly south of city B. A bus, beginning at city A travels 50 km at 37 north of east to reach city C. How far, and in what direction must the bus go from city C to reach city B? A) 20 km, west B) 40 km, west C) 80 km, west D) 40 km, east E) 80 km, east 6. A Canadian goose flew 845 km from Southern California to Oregon with an average speed of 30.5 m/s. How long, in hours, did it take the goose to make this journey? A) 27.7 h B) 8.33 h C) 66.1 h D) 462 h E) 7.70 h 7. An object moving along a straight line is decelerating. Which one of the following statements concerning the object's acceleration is necessarily true? A) The value of the acceleration is positive. B) The direction of the acceleration is in the same direction as the displacement. C) An object that is decelerating has a negative acceleration. D) The direction of the acceleration is in the direction opposite to that of the velocity. E) The acceleration changes as the object moves along the line. 8. A ball is dropped from rest from a tower and strikes the ground 125 m below. Approximately how many seconds does it take for the ball to strike the ground after being dropped? Neglect air resistance. A) 2.50 s B) 3.50 s C) 5.05 s D) 12.5 s E) 16.0 s 9. A park ranger wanted to measure the height of a tall tree. The ranger stood 6.10 m from the base of the tree; and he observed that his line of sight made an angle of 73.5 above the horizontal as he looked at the top of the tree. What is the height of the tree? A) 5.84 m B) 8.77 m C) 11.7 m D) 17.3 m E) 20.6 m Page 2

3 10. A 810-kg car accelerates from rest to 27 m/s in a distance of 120 m. What is the magnitude of the average net force acting on the car? A) 740 N B) 2500 N C) 91 N D) 1300 N E) 7900 N 11. A rock is thrown straight up from the earth's surface. Which one of the following statements concerning the net force acting on the rock at the top of its path is true? A) It is equal to the weight of the rock. B) It is instantaneously equal to zero newtons. C) Its direction changes from up to down. D) It is greater than the weight of the rock. E) It is less than the weight of the rock, but greater than zero newtons. 12. A 20-kg crate is suspended from a fixed beam by two vertical ropes. What is the tension in each rope? A) 10 N B) 40 N C) 100 N D) 200 N E) 390 N 13. A 4-kg block and a 2-kg block can move on the horizontal frictionless surface. The blocks are accelerated by a +12-N force that pushes the larger block against the smaller one. Determine the force that the 2-kg block exerts on the 4-kg block. A) 12 N B) 4 N C) 0 N D) +4 N E) +8 N Page 3

4 14. A ball moves with a constant speed of 4 m/s around a circle of radius 0.25 m. What is the period of the motion? A) 0.1 s B) 0.4 s C) 0.7 s D) 1 s E) 2 s 15. A 0.25-kg ball attached to a string is rotating in a horizontal circle of radius 0.5 m. If the ball revolves twice every second, what is the tension in the string? A) 2 N B) 5 N C) 7 N D) 10 N E) 20 N 16. A plane is traveling at 200 m/s following the arc of a vertical circle of radius R. At the top of its path, the passengers experience "weightlessness." To one significant figure, what is the value of R? A) 200 m B) 1000 m C) 2000 m D) 4000 m E) m 17. A woman stands on the edge of a cliff and throws a stone vertically downward with an initial speed of 10 m/s. The instant before the stone hits the ground below, it has 450 J of kinetic energy. If she were to throw the stone horizontally outward from the cliff with the same initial speed of 10 m/s, how much kinetic energy would it have just before it hits the ground? A) 50 J B) 100 J C) 450 J D) 800 J E) 950 J A block of mass m is released from rest at a height R above a horizontal surface. The Page 4

5 acceleration due to gravity is g. The block slides along the inside of a frictionless circular hoop of radius R. 18. Which one of the following expressions gives the speed of the block at the bottom of the hoop? A) zero m/s 2 B) v = mgr mg C) v = 2R 2 2 g D) v = R E) v 2 = 2gR 19. What is the magnitude of the normal force exerted on the block by the hoop when the block has reached the bottom? A) zero newtons B) mg 2 /R C) mg D) 2mg E) 3mg 20. The speed of sound in a certain metal block is m/s. The graph shows the amplitude (in meters) of a wave traveling through the block versus time (in milliseconds). What is the wavelength of this wave? A) 0.5 m B) 1.5 m C) 3.0 m D) 4.0 m E) 6.0 m Page 5

6 Answer Key 1. D 2. E 3. C 4. B 5. B 6. E 7. D 8. C 9. E 10. B 11. A 12. C 13. B 14. B 15. E 16. D 17. C 18. E 19. E 20. E Page 6