用微积分可以算出来:
因瞬时角加速度a=dw/dt,
又有力平衡方程:M=-I*a,
即:-kw=-I*a=-I*dw/dt;
于是:kw = I*dw/dt,
则dt = (dw/w)*I/k,
代入初始条件:t = 0时,w = W
及终止条件:t = t0时,w = W/2
两边积分有:t(0 -> t0)= ln(w)*I/k (W -> W/2);
即:t0 = [ln(W)-ln(W/2)]*I/k = (I*ln2)/k为所求
用微积分可以算出来:
因瞬时角加速度a=dw/dt,
又有力平衡方程:M=-I*a,
即:-kw=-I*a=-I*dw/dt;
于是:kw = I*dw/dt,
则dt = (dw/w)*I/k,
代入初始条件:t = 0时,w = W
及终止条件:t = t0时,w = W/2
两边积分有:t(0 -> t0)= ln(w)*I/k (W -> W/2);
即:t0 = [ln(W)-ln(W/2)]*I/k = (I*ln2)/k为所求