Câu 42: Một vật dao động điều hòa x co t = + 12 s(2 )  
(cm). chọn gốc thời gian lúc vật qua vị trí có li độ +6 cm theo chiều dương.
Giá trị của

là:A
3
rad 
 = − B.
2
3
 =  rad C.
2
3
 = −  rad
D.
3
 =  rad

Wo small variable-thrust jets are actuated to keep the spacecraft angular velocity about the z-axis constant at ? 0 = 1.16 rad/s as the two telescoping booms are extended from r1 = 1.18 m to r2 = 4.69 m at a constant rate over a period of 124 seconds. the small 19-kg experiment modules at the ends of the booms may be treated as particles, and the mass of the rigid booms is negligible. determine the necessary thrust t for each jet as a function of time where t = 0 is the time when the telescoping action is begun. after you have the general expression for t, answer the questions. show work.