天同師兄,你係http://hk.knowledge.yahoo.com/question/question?qid=7011033100279 曾解答左小弟Static Equilibrium 既問題,但我有幾個地方想請教,希望你可以解一解答,唔該!
1."This force R is in a direction perpendicular to the tension T and is pointing towards the vertical that shown on the diagram." 有關呢句小弟有d唔明點解佢同時係R = mg.sin(theta) 而且又係圖中垂直向上既R.
2.大概小弟對向量問題唔純熟,係師兄係話resultant force R such that R = mg.sin(theta). 如果係咁咪姐係mg>T ?想請問點解會作出咁既假設 T不是有機會>mg的嗎?
3.小弟計算時,是將T cos(theta) balance左mg, ie.T cos(theta) =mg, resultant force,F=R'=Tsin(theta). BY solving,F=mg tan(theta) ,既然不知道(theta)的值,為何可以肯定 mg.sin(theta)<mg tan(theta)