Tham khảo tài liệu 'sat ii physics (sn) episode 1 part 3', ngoại ngữ, ngữ pháp tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 10. . A woman runs 40 m to the north in s and then 30 m to the east in s. What is the magnitude of her average velocity A B C D E m s m s m s m s m s Explanations 1. C Displacement is a vector quantity that measures the distance between the starting point and ending point not taking the actual path traveled into account. At the end of four laps the athlete will be back at the starting line for the track so the athlete s total displacement will be zero. 2. D Statement I refers to distance not displacement since the five-mile distance is along a winding road and does not describe a straight-line path. Both statements II and III however contain a reference to displacement. The altitude of a town is a measure of the straight-line distance between the town and sea level. As the crow flies is a common way of saying in a straight-line path. Neither statement II nor statement III describes a certain route between the two points in question they simply describe how far apart those two points are. 3. A Average velocity is a measure of total displacement divided by total time. Total displacement is the distance separating the starting point and the finishing point. Since the car both starts and finishes at point A its total displacement is zero so its average velocity is also zero. 4. B Average speed is a measure of total distance traveled divided by the total time of the trip. Solving this problem calls for a single calculation 5. E 51 The force of air resistance against a ball increases as the ball accelerates. At a certain point the force of air resistance will be equal to the force of gravity and the net force acting on the ball will be zero. At this point its velocity will remain constant. This velocity is known as an object s terminal velocity and it explains why in real life many falling objects don t continue accelerating all the way to the ground. 6. C Acceleration is a measure of the change in velocity over time. The car s change in .
