Falling Objects (vertical motion) 9-- 718 m/s * 4-10 1. The John Hancock Center in Chicago is the tallest building in the United States in which there are residential apartments, Suppose a resident accidentally causes a chunk of ice to fall from the roof. Vi = Omls a, What would be the velocity of the ice after 10 s as it hits the ground? Neglect air resistance. V( = (.8) (10) Vca ? BY = ? b. How far would the chunk of ice fall during this time? BY OHIOS) + (0.5) (9.8 m/ 9( 10: )2 ay- - 490m 1--9.8 2. The Sears Tower in Chicago is 443 m tall. Suppose a book is dropped from the top of the building S = 7 a. What would be the book's velocity at a point 221 m above the ground? Neglect air resistance. V-2. 92 + 2(-9.8mig#) (222 m ) VI = 0 VEZ =1- 4 3 51,2 VA -66mls b. How long would it take the book be at a point 221 m above the ground? c = ? VF = Vc+gt t = + CG mils by= 222m 9:8 m / 5 2 6: 73 s - 6 6m / s = 0+ (9: 8mls ? ) (t ) = - 98 m/62 3. The Westin Stamford Hotel in Detroit is 228 m tall. If a worker on the roof drops a sandwich. a. How long does it take the sandwich be at a point 80 m above the ground? NF - virat 6 : 1 - 54mls = 0 + (- 9. 8m/(" ) (6)) E= 5.515 or 65 b. What is the final velocity of the sandwich at a point 80 m above the ground? =143m VF 2 = 02 + 2( - 9.8 m/s ?) [148m) VAT = V- 29008 VF =- 54 m/s 4. Your sister throws the house keys up to you from the second-floor window. You miss to catch them. If it takes 2.5 s from the time when your sister throws the keys up to you until she catches the same keys - 255 on the way back down, what is the keys' a. Initial velocity? o = V( (2.5)+ 0/5( 9,8)(2.5)2 - 2.5 Vis - 49.252 = Vi = 12.3 b. final velocity? Ve = - 12. 2 In C. What is the maximum height of the keys thrown up? 03= 12.32 +2(- 9.8) AY - 151.3= 196 BY - 9.8m/52 5. A student trying out for the football team kicks the football straight up in the air. The ball hits him on 3.05 the way back down. If it took 3.0 s from the time when the student punted the ball until he gets hit by the ball, what was the football's a. initial velocity? . 5 (-Q.8)(3.0)? - 3.0 vi = - 30.625 = VC = 10.210 b. final velocity? V = - 19.19 c. What is the maximum height of the thrown football? 0 2 = (10,21)2 6 20-9.8) (AY) 3104. 2441 1-19. 6 OV) AY = 5.32 m - 104- 24111 8 - 19.6 AY -9.8 m/s a 6. A ball is thrown upward from the ground with an initial velocity of 50.0 meters per second. a. How long will it take the ball to strike the ground? = 50.0mus b. What will be the velocity of the ball just before it strikes the ground? c. What is the maximum height of the thrown ball?7. A box of books is thrown upward from the ground with initial velocity of 10 m/s a. How long will it take for the box to strike the ground? b. What will be the velocity of the box just before it strikes the ground? c. What is the maximum height of the box? 8. A robot probe drops a camera off the rim of a 340 m high cliff on Mars, where the free-fall acceleration is - 3.7 m/s'. a. Find the velocity with which the camera hits the ground. b. Find the time required for it hit the ground. 9. A hiker throws a rock up with initial velocity of 8 m/s from a 40 m tall cliff. a. How long will it take to hit the ground? b. How was its velocity upon impact? 10. A rock is thrown upward from a 50 m cliff with initial velocity of 15 m/s. a. How long will it take to hit the ground? b. Find the velocity of the rock before it hits the ground. 11. You decide to flip a coin to determine whether to do you Physics or World History homework first. The coin is flipped straight up. a. If the coin reaches the high point 0.30 m above, what was its initial speed? b. If you catch it at the same time as you released it, how much time did it spend it the air? Bonus. A ball is thrown upward from the ground with an initial speed of 25 m/s at the same instant, a ball is dropped from rest from a building 15 m high. After how long will the balls be at the same height? A scout boy is rising steadily from rest with acceleration of 1.7 m/s'. After 10 s he reaches the top of a cliff and drops his bag pack on the ground. a. What is the velocity of the bag pack before it hit the ground? b. How long it takes the bag pack to hit the ground