1.某质点沿x轴做直线运动,其加速度随时间的变化-|||-规律为: =-(k)^2t ,式中k为大于零的常量,v是质点-|||-的运动速度,t是时间。已知当 t=0 时,质点的初速-|||-度为v0,则该质点的速率v与时间t的函数关系是(-|||-)-|||-A =dfrac (1)(2)k(t)^2+(v)_(0)-|||-B =-dfrac (1)(2)h(t)^2+(v)_(0)-|||-C dfrac (1)(v)=dfrac (1)(2)k(t)^2+dfrac (1)({v)_(0)}-|||-D dfrac (1)(v)=-dfrac (1)(2)k(t)^2+dfrac (1)({v)_(0)}