Thehelicopterinthedrawingismovinghorizontallytotherightataconstantvelocity.TheweightofthehelicopterisW=53800N.TheliftforceLgeneratedbytherotatingblademakesanangleof21.0degreewithrespecttothevertical.(a)Whatis

Question

The helicopter in the drawing is moving horizontally to the right at a constant velocity.The weight of the helicopter is W=53800N.The lift force L generated by the rotating blade makes an angle of 21.0 degree with respect to the vertical.
(a) What is the magnitude of the lift force?
(b) Determine the magnitude of the air resistance R that opposes the motion
丨 /L
丨 /
丨21度 /
丨 / v
R
丨
丨
丨
W
A cable is lifting a construction worker and a crate,as the drawing shows.The weights of the worker and crate are 965 and 1510 N,respectively.The acceleration of the cable is 0.620m/s^2,upward.What is the tension in the cable.
(a) Below the worker and
(b) Above the worker?
第二题是向上作加速运动

Answer 1

问题的意思就是:一架直升机匀速向右飞行.受的是螺旋桨的斜向右(与垂直角度偏21度)的拉力.问拉力的大小和相应空气阻力R是多少.
所以
答案:拉力L=53800/cos21
阻力R=53800tg21 阻力与拉力的水平分力相等
第二题 哦,那就好了
是讲一个绳缆拽着一个工人和一个箱子.因为是向上作加速运动.问绳缆的张力是多大,方向是在工人上头,还是下面.
则张力tension=mg+ma=[(1510+965)/g]*(g+a)
其中m=(1510+965)/g,g=9.8m/s^2
方向向上,选(B)