F.4 Phy mechanics

May I offer an alternative solution:

Resolve the normal force N2 into vertical and horizontal components. The vertical component = (N2)cos(a), and horizontal component = (N2).sin(a), where a is the angle of slope.

Thus, in equilibrium both horizontally and vertically, we have
Horizontally: N1 = (N2).sin(a)
Vertically: mg = (N2).cos(a)

By squaring both equations and then adding them together,
(N1)^2 + (mg)^2 = (N2)^2[(sin(a))^2 + (cos(a))^2]
i.e. (N1)^2 + (mg)^2 = (N2)^2 since sin(a))^2 + (cos(a))^2 = 1

有人問過而我又答了一次。

請參考 :

http://hk.knowledge.yahoo.com/question/question?qid=7014012200199

2014-02-06 18:18:07 補充：
其實可不可以用equation去證明N2^2=N1^2+(mg)^2?

唔明你的意思。

對於力學，要用向量，一定要加入方向去計算。