試題詳解

9.A certain pendulum consists of a 1.5-kg mass swinging at the end of a string (length=2.0m).At the lowest   point in the swing the tension in the string is equal to 20 N. To what maximur e this lowest point will the mass rise during its oscillation? Note that the accele gravity g = 9.8 m/s².
(A) 77 cm
(B) 50 cm
(C) 63 cm
(D) 36 cm
(E) 95 cm