本文主要讨论了滑动摩擦、风阻对物体沿斜面、圆弧和最速降线等轨道下滑时间的影响，定量分析了下滑时间与阻力相关参数的依赖关系，以及圆弧轨道半径最速优化的相关问题. 最速降线是基于物体在无阻力条件下得到的最快下滑轨道，而考虑滑动摩擦力和风阻的数值结果表明，下滑时间与摩擦系数、风阻表达式、始末位置连线的斜率都有关，当风阻大小与速度平方成正比时，圆弧或直线轨道在一定条件下更快. 另一方面，以圆盘和球壳为例，定量讨论了滚动和质量分布对下滑时间的影响，滚动下滑总时间与物体沿光滑轨道下滑总时间的比值决定于圆环和球壳的质量密度分布函数和内外半径之比，与半径的绝对大小无关.

We performe the dynamics analysis on sliding down time that affected by resistance. The famous branchistochrone is the fastest path which is obtained by ignoring resistance. Considering the sliding friction resistance and air resistance,we find that the sliding down time depends on the friction coefficient,amplitude of air restance, mass of object and slope of motion path. The sliding down time could be optimized by the radius of the circular orbital. On the other hand,  the scrolling down could also shorten the sliding down time, we also quantitatively investigate the scrolling time affects by the mass distribution of the disk and spherical shell, the mass distribution origins from the mass density and shape of the objects. The ratio of scrolling time to sliding time is decided by the function of mass density and the ratio of inside radii to outside radii.