Fa=Fb=10N,M=1kg,求甲乙兩圖分別上升三公尺後的瞬時速率?
甲
Fa = 10N , S = 3
M = 1 kg , h = 3
v0 = 0, v = ?
FaS = mgh + (1/2)mv² - (1/2)mv0²
10 * 3 = 1*9.8*3 + (1/2)1*v²
v² = 1.2 , v = 1.1 左右
乙的話
Fb = 10N , S = 5
M = 1 kg , h = 3
v0 = 0, v = ?
功 = FbS
FbS = mgh + (1/2)mv² - (1/2)mv0²
自己算吧 |
