Chapter 2 Review Answers Section 1 Reinforcement Describing Motion 8. positive – 1. e 9. negative 2. b 10. zero 3. a and c 4. d 5. walking home 6. You can tell an object has moved because its position has changed. 7. Displacement is how far and in what direction an object has from its starting Section 3 Reinforcement Motion and Forces – point. 1. is a push or a pull that one object exerts 8. Instantaneous speed indicated on the on another. speedometer. 2. (Answers will vary.) Examples might include 9. A horizontal line on a distance-time graph fingers on pencil; body on chair; feet on indicates that an object is stationary. floor; atmosphere on body. 10. Speed is calculated by dividing the distance 3. The direction of the motion will change in moved by the time elapsed. the direction of the force. 11. A race car driving around a track at 240 4. It is the net force. km/h can have a constant speed. 5. The forces are balanced. The forces acting on the rock are not 6. Section 2 Reinforcement Acceleration – balanced; the net is not zero. 1. Acceleration is the rate of change of It is the tendency of an object to resist any 7. velocity. change in its motion. 2. It accelerates when it changes its Velocity changes when the object speeds up, 8. and/or direction. slows down, or changes direction. 3. Positive acceleration occurs when an Its mass determines its inertia. 9. object’s speed increases; negative 10. An object moving at constant velocity acceleration occurs when an object’s speed continues to move at that velocity until a net decreases. force acts on it. 4. change in velocity (final velocity minus initial velocity) divided by time Key Terms Chapter 2: Motion 5. meters/second/second (m/s/s); – (Crossword Puzzle) meters/second2 (m/s2) 6. acceleration 7. a = (vf vl)/t = (9 m/s 3 m/s)/3s – – = 2 m/s2
Chapter 2 Review Answers Section 1 Reinforcement – Describing Motion 1. e 2. b 3. a and c 4. d 5. walking home 6. You can tell an object has moved because its position has changed. 7. Displacement is how far and in what direction an object has from its starting point. 8. Instantaneous speed indicated on the speedometer. 9. A horizontal line on a distance-time graph indicates that an object is stationary. 10. Speed is calculated by dividing the distance moved by the time elapsed. 11. A race car driving around a track at 240 km/h can have a constant speed. Section 2 Reinforcement – Acceleration 1. Acceleration is the rate of change of velocity. 2. It accelerates when it changes its and/or direction. 3. Positive acceleration occurs when an object’s speed increases; negative acceleration occurs when an object’s speed decreases. 4. change in velocity (final velocity minus initial velocity) divided by time 5. meters/second/second (m/s/s); meters/second2 (m/s2) 6. acceleration 7. a = (vf – vl)/t = (9 m/s – 3 m/s)/3s = 2 m/s2 8. positive 9. negative 10. zero Section 3 Reinforcement – Motion and Forces 1. is a push or a pull that one object exerts on another. 2. (Answers will vary.) Examples might include fingers on pencil; body on chair; feet on floor; atmosphere on body. 3. The direction of the motion will change in the direction of the force. 4. It is the net force. 5. The forces are balanced. 6. The forces acting on the rock are not balanced; the net is not zero. 7. It is the tendency of an object to resist any change in its motion. 8. Velocity changes when the object speeds up, slows down, or changes direction. 9. Its mass determines its inertia. 10. An object moving at constant velocity continues to move at that velocity until a net force acts on it. Key Terms – Chapter 2: Motion (Crossword Puzzle)
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