110 CHAPTER 4 TWO-DIMENSIONAL KINEMATICS to the east. (a) How much time does the pilot have to make the alti- 13. . Victoria Falls The great, gray-green, greasy ZambeziaRiver flows tude change without crashing into the hill? (b) What minimum, over Victoria Falls in south central Africa. The falls are approxi- constant, upward acceleration is needed in order to clear the hill? mately 108 m high. If the river is flowing horizontally at 3.60 m/s (c) What are the horizontal and vertical components of the bal- just before going over the falls, what is the speed of the water when loon's velocity at the instant that it clears the top of the hill? it hits the bottom? Assume the water is in free fall as it drops. 8. . . An electron in a cathode-ray tube is traveling horizontally at 14. A diver runs horizontally off the end of a diving board with an 2.10 X 10' cm/s when deflection plates give it an upward accel- initial speed of 1.85 m/s. If the diving board is 3.00 m above the eration of 5.30 x 10 7cm/s'. (a) How much time does it take for water, what is the diver's speed just before she enters the water? the electron to cover a horizontal distance of 6.20 cm? (b) What is its vertical displacement during this time? 15. . An astronaut on the planet Zircon tosses a rock horizontally with a speed of 6.95 m/s. The rock falls through a vertical distance of . Two canoeists start paddling at the same time and head toward 1.40 m and lands a horizontal distance of 8.75 m from the astro- a small island in a lake, as shown in FIGURE 4-18. Canoeist 1 paddles naut. What is the acceleration due to gravity on Zircon? with a speed of 1.10 m/s at an angle of 45 north of east. Canoe- ist 2 starts on the opposite shore of the lake, a distance of 1.5 km 16. . . Predict/Calculate Pitcher's Mounds Pitcher's mounds are raised due east of canoeist 1. (a) In what direction relative to north must to compensate for the vertical drop of the ball as it travels a hori- canoeist 2 paddle to reach the island? (b) What speed must canoeist zontal distance of 18 m to the catcher. (a) If a pitch is thrown hori- 2 have if the two canoes are to arrive at the island at the same time? zontally with an initial speed of 32 m/s, how far does it drop by the time it reaches the catcher? (b) If the speed of the pitch is increased, does the drop distance increase, decrease, or stay the same? Explain. (c) If this baseball game were to be played on the Moon, would the drop distance increase, decrease, or stay the same? Explain. . . Playing shortstop, you pick up a ground ball and throw it to sec- ond base. The ball is thrown horizontally, with a speed of 18 m/s, directly toward point A (FIGURE 4-19). When the ball reaches the second baseman 0.54 s later, it is caught at point B. (a) How far were you from the second baseman? (b) What is the distance of vertical drop, AB? 1.0 km 1 1450 1.5 km FIGURE 4-19 Problem 17