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Tham khảo tài liệu 'physics_test_bank_split_9', khoa học tự nhiên, vật lý phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Simpo PDF Merge and Split Unregistered Version - http www.simpopdf.com 5. The center of mass of Earth s atmosphere is A. a little less than halfway between Earth s surface and the outer boundary of the atmosphere B. near the surface of Earth C. near the outer boundary of the atmosphere D. near the center of Earth E. none of the ab ove ans D 6. A thick uniform wire is bent into the shape of the letter U as shown. Which point indicates the location of the center of mass of this wire A B D E C ans B 7. A machinist starts with three identical square plates but cuts one corner from one of them two corners from the second and three corners from the third. Rank the three plates according to the x coordinate of their centers of mass from smallest to largest. y I x 2 3 1 A. 1 2 3 B. 1 and 2 tie then 3 C. 1 then 2 and 3 tie D. 3 2 1 E. 1 and 3 tie then 2 ans E Chapter 9 CENTER OF MASS AND LINEAR MOMENTUM 121 Simpo PDF Merge and Split Unregistered Version - http www.simpopdf.com 8. Block A with a mass of 4 kg is moving with a speed of 2.0 m s while block B with a mass of 8 kg is moving in the opposite direction with a speed of 3m s. The center of mass of the two block-system is moving with a velocity of A. 1.3 m s in the same direction as A B. 1.3 m s in the same direction as B C. 2.7m s in the same direction as A D. 1.0 m s in the same direction as B E. 5.0 m s in the same direction as A ans B 9. At the same instant that a 0.50-kg ball is dropped from 25 m above Earth a second ball with a mass of 0.25 kg is thrown straight upward from Earth s surface with an initial speed of 15m s. They move along nearby lines and pass each other without colliding. At the end of 2.0 s the height above Earth s surface of the center of mass of the two-ball system is A. 2.9m B. 4.0m C. 5.0m D. 7.1m E. 10.4 m ans D 10. At the same instant that a 0.50-kg ball is dropped from 25 m above Earth a second ball with a mass of 0.25 kg is thrown straight upward from Earth s surface with an initial speed