如图质子和α粒子都从静止开始,经AB间电场加速后垂直进 入CD间的匀强电场,到离开电场为止,在CD间的偏转距离分别为y1、y2,动能的变化量分别为△E1和△E2,则y1:y2及△E1:△E2的值为( )
A:1:2;1:1
B:1:2;1:4
C:1:1;1:2
D:2:1;4:1
已知:在Rt△ABC中,∠C=90°,sinA、sinB是方程x2+px+q=0的两个根.
Sara walked in fear, because she felt that someone was following her.
对于密度公式ρ=ρ=mv的正确理解为()