If you work harder, you'll have another______ to play the violin at a concert.
A:sleep
B:chance
C:mistake
D:problem
如图所示一根劲度系数k=200N/m的轻质弹簧拉着质量为m=0.2kg的物体从静止开始沿倾角为θ=37°的斜面匀加速上升,此时弹簧伸长量x=0.9cm,在t=1.0s内物体前进了s=0.5m.求: