Physics 104S12 Guide Lines for Exam 2 phy104s12. Class Exam

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1 Physics 104S12 Guide Lines for Exam 2 phy104s12 When: March 7 th 11 11:50 PM Class Exam Where: Normal Classroom Chapters: 4 and 5 Format: 25 multiple choice questions Bring: Green Scantron Sheet, Calculator, #2 pencils Provided: Constants, conversions factors and scrap paper Study Aid: Sample questions for practice are provided Do not assume that any of these questions will be repeated in the exam, they are provided to help you prepare, review and gauge yourself. When: March 7 th 2 5 PM Laboratory Exam Where: Lab room 235 and 236 Chapters: 1, 2, 3, 4 and 5 Format: 5 Questions Part 1: Questions will be like homework problems in which you will have to show all the relevant work. Part2: Questions will be over laboratory related material. You will be asked to setup and perform and experiment and answer questions and do derivations and calculations. Please be aware that you will be asked to go to a specific station to perform your experiment and you will have limited time to complete your experiment. Partial credit will be given based on your effort, relevance to the questions, neatness, and clear explanations. Bring: Text book, Calculator, #2 pencils. You can also bring one page (both sides) of notes on laboratory experiments (not solutions to questions or homework problems are allowed) you will be asked to turn it this page. Study Aid: Sample questions for practice are provided Do not assume that any of these questions will be repeated in the exam, they are provided to help you prepare, review and gauge yourself.

2 Practice questions for class exam Multiple Choices Identify the choice that best completes the statement or answers the question. 1. Which of the following is an example of the type of force that acts at a distance? a. gravitational b. magnetic c. electrical d. all of the above 2. An astronaut applies a force of 500 N to an asteroid, and it accelerates at 7.00 m/s 2. What is the asteroid's mass? a. 71 kg b. 135 kg c. 441 kg d kg 3. A rock is rolled in the sand. It starts at 5.0 m/s, moves in a straight line for a distance of 3.0 m, and then stops. What is the magnitude of the average acceleration? a. 1.8 m/s 2 b. 4.2 m/s 2 c. 5.4 m/s 2 d. 6.2 m/s 2 4. A baseball batter hits an incoming 40-m/s fastball. The ball leaves the bat at 50 m/s after a ball-on-bat contact time of s. What is the force exerted on the 0.15-kg baseball? a. 450 N b. 250 N c. 90 N d. 50 N 8. A box of mass m is placed on an incline with angle of inclination. The box does not slide. The magnitude of the frictional force in this case is: a. s mg sin b. mg cos c. mg sin d. not given. 9. The unit of work, joule, is dimensionally the same as: a. newton/second. b. newton/kilogram. c. newton-second. d. newton-meter. 10. I use a rope 2.00 m long to swing a 10.0-kg weight around my head. The tension in the rope is 20.0 N. In half a revolution how much work is done by the rope on the weight? a J b. 126 J c. 251 J d Which of the following is an example of a nonconservative force? a. gravity b. magnetism c. friction d. Both choices A and B are valid. 5. A 15-kg block rests on a level frictionless surface and is attached by a light string to a 5.0-kg hanging mass where the string passes over a massless frictionless pulley. If g = 9.8 m/s 2, what is the tension in the connecting string? a. 65 N b. 17 N c. 49 N d. 37 N 6. A 100-kg box is placed on a ramp. As one end of the ramp is raised, the box begins to move downward just as the angle of inclination reaches 15. What is the coefficient of static friction between box and ramp? a b c d Two objects, A and B, are placed on an inclined plane that can be rotated to different angles of elevation. A starts to slide at twice the angle of elevation that B starts sliding. The respective coefficients for static friction for A and B are A and B. Choose the last answer that is correct. a. B > A b. A > B c. B = 2 A d. A = 2 B 12. If both mass and velocity of a ball are tripled, the kinetic energy is increased by a factor of: a. 3. b. 6. c. 9. d What is the minimum amount of energy required for an 80-kg climber carrying a 20-kg pack to climb Mt. Everest, m high? a MJ b MJ c MJ d MJ 14. An amount of work equal to 1.5 J is required to compress the spring in a spring-gun. What is the "launch speed" of a 15-g marble? a. 14 m/s b. 15 m/s c. 18 m/s d. 21 m/s 15. I drop a 60-g golf ball from 2.0 m high. It rebounds to 1.5 m. How much energy is lost? a J b J c J d. 1.0 J

3 sample exam1 question phy104s12 - goderya Answer Section MULTIPLE CHOICE 1. ANS: D DIF: 1 2. ANS: A DIF: 1 3. ANS: B DIF: 2 4. ANS: A DIF: 2 5. ANS: D DIF: 3 TOP: 4.5 Applications of Newton's Laws 6. ANS: B DIF: 2 TOP: 4.6 Forces of Friction 7. ANS: B DIF: 2 TOP: 4.6 Forces of Friction 8. ANS: C DIF: 3 TOP: Conceptual Problems 9. ANS: D DIF: 1 TOP: 5.1 Work 10. ANS: D DIF: 2 TOP: 5.1 Work 11. ANS: C DIF: 1 TOP: 5.2 Kinetic Energy and the Work-Energy Theorem 12. ANS: D DIF: 1 TOP: 5.2 Kinetic Energy and the Work-Energy Theorem 13. ANS: A DIF: 2 TOP: 5.3 Gravitational Potential Energy 14. ANS: A DIF: 2 TOP: 5.4 Spring Potential Energy 15. ANS: A DIF: 2 TOP: 5.5 Systems and Energy Conservation

4 Laboratory Exam Part 1 1. Determine the resultant of the three forces provided using the force table. Then calculate the resultant using the algebraic method. Compare the two resultants. Explain which method is more reliable. A B C Problem Set Magn. (gmf) Angle (deg) Magn. (gmf) Angle (deg) Magn. (gmf) Angle (deg) Activity 2: (35 points) suppose you missed a lab on Newton s Second Law and you have arranged to do a makeup lab on your own. The instructor has provided on your computer station a 2 meter PASCO track, a super pulley, a Cart with a plunger, 80 grams of mass, and a stop watch that can measure up to 100 of a second. You noticed that the instructor did not provide the picket fence and the Photogates. You also know that your instructor had to leave for another engagement and there is no one else to help you secure additional equipment. You sit in the lab thinking how you are going to complete the makeup lab with what whatever equipment you have. From your knowledge of Newton s second law you know that in order to do the experiment you need to collect data on acceleration of the Cart for different forces, while keeping the mass of the System constant. After some thought you realize that you actually do not need the picket fence and Photogates to do the experiment and that you can still measure the acceleration of the Cart for different forces using the meter scale on the track and the digital stop watch. a. Write the equation that is applicable to this experiment to measure the acceleration of the Cart. The question is asking to use kinematics to use the equipment to determine the acceleration. No need to use Newton s Laws. Note measure the acceleration not derive. 1 2 x vt i at 2 b. Simplify the equation (acceleration on left hand side and everything else on right hand side) to find the acceleration of the Cart in terms of other quantities. From equation of part 1 just manipulate the equation to keep a on one side and everything else on the other side, note that initial velocity would be zero to make the measurement easier. 2 x a 2 t c. What initial condition(s) will you have to set? Level the track to remove the acceleration due to incline, than find the number of paperclips that takes to just overcome friction force. Also set initial velocity is zero d. What parameter(s) in your equation for acceleration are kept fixed? Δx is kept fixed, Mass of the system, initial velocity in each run should be kept to zero.

5 e. What quantity(s) will you measure? time, Mass of the cart and paper clips f. How will you improve the accuracy of your measurement of acceleration Make several trials for acceleration for each force and use the average acceleration? The level of the track can also affect the results. g. Suppose you performed the experiment and get the following data; with the equation y = A + B x where A=00027 and B = and y is the force. What are the units for B. What physical quantity does A represent in the above equation? Force in Newton s Acceleration in m/s B= kg, A= Friction Force Part 2 3. A home run is hit in such a way that the baseball just clears a wall 21 m high, located 130m from home plate. The ball is hit at an angle of 35degrees to the horizontal, and air resistance is negligible. Find a. The initial speed of the ball, Ans: 42 m/s b. the time it takes the ball to reach the wall Ans: 3.8s c. The velocity components and the speed of the ball when it reaches the wall. (Assume the ball is hit at a height of 1.0 m above the ground.) Ans: V x = 34 m/s, V y = 13 m/s, V=37 m/s 4. Find the tension in each cable supporting the 520 N cat burglars in Figure 2. Assume the angle θ of the inclined cable is 34.0.

6 T 2 = 930 N in the inclined cable T 1 = (930 N) cos(34.0 ) = 771 N in the horizontal cable 5. Two blocks are fastened to the ceiling of an elevator as in Figure 1. The elevator accelerates upward at 2.00 m/s 2. The blocks both have a mass of 10.0 kg. Find the tension in each rope. Solution or Explanation Ans T lower =118 N T upper =240 N