2. A 0.40-kg mass attached to the end of a string swings in a vertical circle having a radius of 1.8 m. At an instant when the string makes an angle of 40 degrees below the horizontal, the speed of the mass is 5.0 m/s. What is the magnitude of the tension in the string at this instant?
(A) 9.5 N
(B) 3.0 N
(C) 8.1 N
(D) 5.6 N
(E) 4.7 N
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統計: 尚無統計資料
統計: 尚無統計資料