The diagram shows a heavy plank hinged to a vertical wall at one end and supported by a strut which inclines at θ=60 to the vertical. The weight of the plank is 200kN,Assume that the thrust from strut acts along it's length.Calculate
(a) the thrust from the strut,and,
(b) size and direction of the force at the hinge.
我唔明點解thrust from strut(a)不等於200000/sin 60...
還有,明明plank係horizontal地放著,但why它唔等於thrust x cos60,,反而係要分什麼Rx and Ry??
圖片參考:http://i83.photobucket.com/albums/j315/kinki_chung/phy2000.jpg