Possible

Possible

所有跟贴·加跟贴·新语丝读书论坛

送交者: gyro 于 2009-09-14, 11:49:18:

回答: 如果不这样用能量守恒立方程，可否先求出CASE 2）的摩擦力？由 @ 于 2009-09-14, 11:36:57:

mdv/dt=mgsin(theta)-F
I*d(omega)/dt=FR

F the friction force, theta the slope angle

Multiply the first eq. by Rv, the second by v, add together. The friction force terms cancel, the resulting equation is the energy conservation.

perfect!这里最容易犯的错误就是把摩擦力当作滑动时的摩擦力了。 (无内容) - @ (0 bytes) 2009-09-14, 12:10:24 (364569)