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# Question

PRACTICE IT Use the worked example above to help you solve this problem. A ball is thrown upward from the top of a building at an angle of 30.00 to the horizontal and with an initial speed of 19.0 m/s. The point of release is h = 46.0 m above the ground. (a) How long does it take for the ball to hit the ground? 4.183 (b) Find the ball's speed at impact. 35.532 m/s (c) Find the horizontal range of the ball 68.829 EXERCISE HINTS: GETTING STARTED M STUCK Suppose the ball is thrown from the same height as in the PRACTICE IT problem at an angle of 34.0 below the horizontal. If it strikes the ground 43.3 m away, find the following. (Hint: For part (a), use the equation for the x-displacement to eliminate vof from the equation for the y-displacement.) (a) the time of flight The x coordinate as a function of time is )cos(34.0), so the initial speed is vo dr/(cos 34.0Δι), where Δ,: 43.3 and Δι is the time of flight. Insert this into your equation for y(1) and solve for the time of flight. Note that the answer should be smaller than 3.064, since the ball is thrown down (and to the right). s (b) the initial speed ake sure you have a fixed coordinate system. For instance, is the origin (0, 0) at the base of the building? If so, then the initial height of the ball is 46.0 m. Is the origin instead at the initial position of the ball? If so, then the ball lands when its y-coordinate is equal to -46.0 m. m/s (c) the speed and angle of the velocity vector with respect to the horizontal at impact speed m/s angle o below the horizontal
PRACTICE IT Use the worked example above to help you solve this problem. A ball is thrown upward from the top of a building at an angle of 30.00 to the horizontal and with an initial speed of 19.0 m/s. The point of release is h = 46.0 m above the ground. (a) How long does it take for the ball to hit the ground? 4.183 (b) Find the ball's speed at impact. 35.532 m/s (c) Find the horizontal range of the ball 68.829 EXERCISE HINTS: GETTING STARTED M STUCK Suppose the ball is thrown from the same height as in the PRACTICE IT problem at an angle of 34.0 below the horizontal. If it strikes the ground 43.3 m away, find the following. (Hint: For part (a), use the equation for the x-displacement to eliminate vof from the equation for the y-displacement.) (a) the time of flight The x coordinate as a function of time is )cos(34.0), so the initial speed is vo dr/(cos 34.0Δι), where Δ,: 43.3 and Δι is the time of flight. Insert this into your equation for y(1) and solve for the time of flight. Note that the answer should be smaller than 3.064, since the ball is thrown down (and to the right). s (b) the initial speed ake sure you have a fixed coordinate system. For instance, is the origin (0, 0) at the base of the building? If so, then the initial height of the ball is 46.0 m. Is the origin instead at the initial position of the ball? If so, then the ball lands when its y-coordinate is equal to -46.0 m. m/s (c) the speed and angle of the velocity vector with respect to the horizontal at impact speed m/s angle o below the horizontal

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