彈簧一物塊直線振動(dòng)系統(tǒng)中,物塊質(zhì)量m,兩根彈簧的剛度系數(shù)各為k1與k2。若用一根等效彈簧代替這兩根彈簧,則其剛度系數(shù)k為:()
A.A B.B C.C D.D
均質(zhì)桿AB長(zhǎng)L,質(zhì)量m,質(zhì)心為C。點(diǎn)D距點(diǎn)A為1/4L。桿對(duì)通過(guò)點(diǎn)D且垂直于AB的軸y的轉(zhuǎn)動(dòng)慣量為:()
點(diǎn)沿軌跡已知的平面曲線運(yùn)動(dòng)時(shí),其速度大小不變,加速度a應(yīng)為:()