圖示的力分別在x、y、z三軸上的投影為()
A.X=-3√2P/10,Y=2√2P/5,Z=-√2P/2; B.X=-2√2P/5,Y=3√2P/10,Z=-√2P/2; C.X=3√2P/10,Y=-2√2P/5,Z=-√2P/2; D.X=2√2P/5,Y=3√2P/10,Z=-√2P/2.
A.X=2√2P/5,Y=3√2P/10,Z=√2P/2 B.X=2√2P/5,Y=-3√2P/10,Z=-√2P/2 C.X=-2√2P/5,Y=3√2P/10,Z=√2P/2 D.X=-2√2P/5,Y=-3√2P/10,Z=√2P/2
圖示為一方桌的對(duì)稱(chēng)平面,水平拉力P和桌子重W都作用在對(duì)稱(chēng)平面內(nèi),桌腿A、B與地面之間的靜滑動(dòng)摩擦系數(shù)為f。若在對(duì)稱(chēng)平面內(nèi)研究桌子所受的滑動(dòng)摩擦力。以下四種情況下哪一種說(shuō)法是正確的?()
A.A B.B C.C D.D