問題詳情
4. A ball rolls down and leaves a slope at an angle of 30°above the horizontal direction. The ballhits the ground 10 seconds later at a point 20 meters below the leaving point, as shown below.How far does the ball travelhorizontally when it hits theground (from point B to pointC)? (Gravitational accelerationg = 10 m/s2)
(A) 623
(B) 835
(C) 936
(D) 1019
(E) 2021
參考答案
用户評論
【面試倒楣鬼-22幸運上後西】評論
這種重計算的放在一分題,最好跳過啦...看了一下數字,也難以速算(ABC選項接近)Vy= V0*sinθ ; Vx= V0*cosθ ,-20 = -(1/2)gt2 +Vy*t =-500+10Vy, Vy=48,則Vx ~=83, X=83*t ~= 835 (B)