題組內容

1. As shown in th figure, two blocks with masses m₁ and m₂ (m₁=2m₂) are connected by a massless string that hangs over a pulley of mass M (M=2m₁) and radius R. The string does not slip. Treat the pulley as a disk.

(b) Assuming that the system starts from rest, find the speed of m₁ after it has fallen by H. 

詳解 (共 1 筆)

助人為本
助人為本
詳解 #7384716
2026/05/26
所以這題可以用兩個方法來解
1.延續上面那題所得到的變數質量m代換為一樣的
也算出直線加速度為g/5
直接套用國中所學過的等加速度直線公式
6a15aea242057.jpg
方法二:能量守恆來解
先求出位能的變化
質量1和質量2的位能變化為2mgh-mgh=mgh
然後動能會等於前面那題有算出總等效質量為5m
所以能量守恆就是位能會等於動能
所以mgh=1/2*5m*v^2
一樣可以得到相同的答案