' I. Velocity ' A physics student at the Super Bowl captures the kickoff on Videotape. The recording is used to measure the location ofthe football at equal time inten'als. (See side View diagram at right.) - ' 1K Initial position of football ' A. Describe in words how the speed of the football varies throughout the motion. In particular. for each of the points A, B, and Q is the speed of the football increasing, decreasing, or (momentarily) staying constant? Explain how you can tell from the diagram: ' ' B. How. if at all. do the horizontal and vertical components of the velocity change during the motion? Explain how you can tell from the diagram. - ' ' C. At each of the labeled points on the diagram (A. :1', A", B, and C ), carefully sketch a vector to represent the instantaneous vetoeity of the football at that point. Use your answers in parts A and B as a guide to sketching your vectors: ' "II. Acceleration " A. In this part you will use the velocity vectors you have drawn at points A' and A" in order to find the direction of the acceleration at point A. ~ 1. In the space at right, copy the velocity vectors Ud and U " with their "tails" together. 2. From these vectors, determine the change in velocity vector, AU, for the motion from point A' to point A". ~ 3. Use the change in velocity vector to draw a vector representing the acceleration from point A' to point A". Explain how you can use the definition of acceleration to support your answer.The vector representing the acceleration of the ball from point A' to point A" also represents the acceleration of the ball at point A. ~ 4. Is the direction of the acceleration vector of the ball consistent with your knowledge of the motion of objects that move under the influence of just gravity? If not, resolve the inconsistency.I B. In the spaces below. use the same reasoning that you used above to determine the direction of the acceleration of the ball at point B and at point C. r ' { I Are your results for the acceleration at points B and C consistent with your answers from part B of section I (in which you described how the horizontal and vertical components of the velocity changed during the motion)? If not. resolve the inconsistencies. "' I C. At each of the points A, B, and C, consider the angle formed when the velocity and acceleration vectors are placed \"tail-to-tail." At each point. is this angle Fargar than, smaiter than. or equal to 90"?\" Point A: Point 3: Point C." ' I D. Generalize your results: Describe briey how an object must be moving if the angle formed by the velocity and acceleration vectors is: f ' I larger than 90\" ' I smaller than 90\" ' I equalto 90 " ' ]I[. Revisiting the car on the oval track ' A race car moves clockwise around the oval track shown at right. The car always moves at constant Speed. Several points Oval track along the track are (Top 1'1'911' (agrmii) labeled.- ' I A. On the diagram. draw vectors to represent the instantaneous velocity of the carat all labeled points. (Note: In drawing your vectors. how should you take into account the fact that the speed is constant?) ' I B. Describe in words how the velocity of the car changes from A\" to A" and from B' to B". Over which interval does the velocity change more?- ' I C. In the space below. use the method that you developed in section I of this worksheet in order to determine the (approximate) direction of the acceleration at point A and at point B.- ' I D. If the car spends the same amount of time between points A' and A" as it does between points 3' and B". would the magnitude of the acceleration be larger at pointA or point B? Explain: ' E. A physics student Tivho is studying acceleration makes the following statement: ' "If an object is moving at a constant speed, the acceleration of the object must be zero_\"r "Would you agree with this statement? If so. explain why. If not~ explain why not. and describe how you modify the statement so that it would be correct