Weight (Pounds) Final Exam Review Answers Questions 1-8 are based on the following information: A student sets out to lose some weight. He made a graph of his weight loss over a ten week period. 180 Weight vs. Time 150 120 90 60 30 0 0 1 2 3 4 5 6 7 8 9 10 Time (Weeks) 1. What is the value of the slope of the graph? -3 2. What are the units of the slope of the graph? Pounds/Week 3. Which of the following statements best represents the meaning of the slope of the graph? For every one week the weight decreases by 3 pounds 4. What is the correct value and units of the vertical axis intercept? 180 pounds 5. Write a statement that represents the meaning of the vertical intercept of the graph. At zero weeks the student weighed 180 pounds 6. Based on the graph, what would be the weight of the baby at 12 weeks? 144 Pounds 7. Write an equation that models the relationship between the weight and the time. Weight = -3(Time) + 180 8. What type of relationship exists between age and weight of a student according to the graph? Linear
Position (m) Final Exam Review Answers Page 2 Questions 9-12 are based on the following information: A student starts out from the classroom door, walks to the end of the hallway 40 meters away and then returns back to the classroom door where he started. The total time for the roundtrip was 80 seconds. 9. The student s displacement for the entire roundtrip walk is: 0 meters 10. The student s total distance traveled for the entire roundtrip walk is: 80 meters 11. The student s average velocity for the entire roundtrip walk is: 0 m/s 12. The student s average speed for the entire roundtrip walk is: 1 m/s Questions 13-15 are based on the information in the following passage: Three physics students are seen walking on the football field. The position vs. time graph on the right describes their motions. 13. Which student is moving the fastest? A his line is the steepest 14. What is the velocity of student C? v = -2 m/s Position (m) 30 20 A C 15. Where relative to the zero line does student B start his trip? 20 meters to the right of the zero line B 16. Write an equation that represents the motion of student A. v = 6t + 0 5 Questions 17-18 are based on the information in the following graph of velocity vs. time for an object: A hungry physics student is heading to lunch at Jimmy John s. For part of the trip they drive their vehicle at a constant speed of 20 m/s for a total of 1000 meters. 17. Draw a position vs. time graph for the motion of the car during the trip? 18. How much time does it take for the student to drive 1000 meters? 50 seconds Questions 19-20 are based on the information in the following graph of velocity vs. time for an object: 19. Describe what is happening to the speed of the object. Speed is decreasing because the velocity is getting smaller. 20. In what direction is the object traveling? The object is traveling to the right because the velocity is positive.
Accel m/s/s) Pos (m) Velocity (m/s) Position (m) Final Exam Review Answers Page 3 Questions 21-24 are based on the information in the following graph of position vs. time for the motion of person A and person B: 21. Who is accelerating? B is moving at a constant speed, A is slowing down 22. Who is moving faster at the beginning? at time = 5 seconds? A is moving faster at the beginning (it is steeper) and B is traveling faster at time = 5 seconds (it is steeper) 23. Who has a larger displacement from zero to 5 seconds? The displacement is the same for both! B A 24. Write a statement about the acceleration of person A and person B in the first 5 seconds. A has constant acceleration (because it is a parabola) and B has zero acceleration (because it is linear) 5 Questions 25-30 are based on the following information: The student from earlier in the test on his way to Jimmy John s applies the brakes so that he can pull into a parking spot. 25 20 25. What is the total displacement of the car as it comes to a stop? Displacement is the area under the velocity line: ½(5)(20) = 50 meters 26. What is the acceleration of the car as it comes to a stop? Acceleration is the slope of the velocity line = -20/5 = -4 m/s/s 15 10 5 0 1 2 3 4 5 27. Draw a position vs. time graphs best represents the car s motion? 28. Draw an acceleration vs. time graphs best represents the car s motion? 29. Draw a motion map arrows best represent the velocity of the car? 30. Draw a motion map arrows best represent the acceleration of the car?
Acceleration Velocity Position Final Exam Review Answers Page 4 Questions 31-34 are based on the following information: A physics teacher is sitting in a low friction chair is moving across the front of the room at a constant speed. He happens to be holding a fire extinguisher in his lap. He points the fire extinguisher away from himself and turn is on for 5 seconds. 31. After he turns on the fire extinguisher the speed of the teacher in the chair will: increase 32. Draw a position vs. time graphs best represents the teacher s motion after he turns on the fire extinguisher? 33. Draw a velocity vs. time graphs best represents the teacher s motion after he turns on the fire extinguisher? Time 34. Draw an acceleration vs. time graphs best represents the teacher s motion after he turns on the fire extinguisher? Time Time Questions 35-42 are based on the following information: An air rocket is launched straight up with an initial velocity of 40 m/s and is allowed to travel to its maximum height and then fall back to the ground as shown to the right. The free fall acceleration due to gravity near the surface of the Earth is 10 m/s/s. 35. Write a sentence that describes the free fall acceleration due to gravity? For every one second of time that passes the velocity of the rocket changes -10 m/s 36. What happens to the speed and acceleration of the rocket on the way down? Speed increases and acceleration remains constant at 10 m/s/s 37. How would the max height and time in the air change if the rocket were launched at half the initial speed? Both max height and time in the air would be less 38. What is the total displacement of the rocket from launch to landing? Zero starts and ends on the ground
Accel m/s/s) vel (m/s) Pos (m) Final Exam Review Answers Page 5 39. Draw a position vs. time graphs best represents the rocket s motion? 40. Draw a velocity vs. time graphs best represents the rocket s motion? 41. Draw an acceleration vs. time graphs best represents the rocket s motion? 42. Draw a motion maps best represents the rocket s velocity? 43. Draw a motion maps best represents the rocket s acceleration?
Final Exam Review Answers Page 6 Questions 44-50 are based on the following information: A car drives off of a cliff with a speed of 20 m/s. The cliff is 45 meters above the beach below. 20 m/s 44. How long does it take the car to hit the ground? 3 seconds 45. If the car were driving off the cliff with an initial velocity of 40 m/s, how would the time in the air compare to the original situation? It would not differ horizontal speed does not affect time in the air. 45 m 46. If the car were driving off the cliff with an initial velocity of 40 m/s, how would the horizontal distance it traveled compare to the original situation? Twice the horizontal speed twice the horizontal distance 47. If the car were twice as massive, how would time in the air compare to the original situation? Nothing would change, mass doesn t affect free fall time 48. How far (horizontally) from the base of the cliff does the car hit the ground? 60 meters 49. What is the velocity in the vertical direction at the instant before it hits the ground? -30 m/s 50. Draw the path of the car from the edge of the cliff to the ground? 51. Consider the point at which the car hits the ground. Which exerts more force; the car on the ground or the ground on the car? They exert the same force on each other N3LPF Questions 52-53 are based on the following information: At the airport a physics student is walking along the moving walkway. The student has a speed of 5 m/s when on a stationary sidewalk and walkway has a speed of 2 m/s. 52. How fast is the student moving relative to a person stopped and standing on the floor? 7 m/s 53. How fast is the student moving relative to a person stopped and also on the walkway? 5 m/s
Final Exam Review Answers Page 7 Questions 54-62 are based on the following information: A student attaches a string to a 2 kg block resting on a frictionless surface, and then pulls steadily (with a constant force) on the block as shown below. Assume no effect of air resistance on the block. 3 kg Point P 54. Write a statement that describes the motion of the block along the table WHILE the student is pulling steadily. The block is speeding up 55. What amount of force would be required to cause the block to move from rest to a have an acceleration of 2 m/s/s? 6 N 56. After the student pulls the block to Point P on the table, the string breaks. The motion of the block AFTER the string breaks could best be described as: The block moves at a constant speed 57. Which exerts more force; the table on the block or the block on the table? They exert the same force on each other N3LPF 58. Which of the following is the weight of the block? (assume g = 10 N/kg) weight = 30 N 59. Name the force(s) acting in the horizontal direction on the block AFTER the string breaks? There are no forces in the horizontal direction! Eventually the block reaches the edge of the table. 60. How is the block speeding up after it has left the table? The block accelerates downward but goes at a constant speed to the right. 61. Suppose that the student sets up the 2 kg block again at rest attached to the string, but this time steadily pulls with twice as much force on the block in the same direction. What could be said of the block s motion while it was being pulled? It would have twice the acceleration 62. Suppose that the same student sets up a block, which is 4 kg, at rest attached to the string, and pulled with the same original force on the block in the same direction. What could be said of the block s motion while it was being pulled? It would have half the acceleration
Final Exam Review Answers Page 8 Questions 63-66 are based on the following information: To test Newton's Laws, two physics students of equal mass sit in low friction chairs (as shown at right.) One student (A) is holding a 16-pound bowling ball. The other student (B) puts her feet on A s knees and pushes off (see picture at the right). 63. Write a statement that best compares the forces of the students. They exert the same force on each other N3LPF 64. Write a statement that best compares the accelerations of the students. Student A has less acceleration because he has more mass 65. Why is it more difficult to get student A to move? More mass means more inertia and more resistance to change in motion 66. If student A took his bowling ball to the moon how would its mass and weight change? The mass (the amount of matter in the ball) would remain the same same ball but it would weigh less because the moon pull objects down less; less gravitational field strength. A B