A helicopter of mass M = 15000 kg is lifting a cubical box of mass m = 2000 kg. The helicopter is going up with an acceleration of `a = 1.2 m//s^(2)`. The four strings are tied at mid points of the sides of the square face PQRS of the box. The strings are identical and form a knot at K. Another string KH connects the knot to the helicopter. Neglect mass of all strings and take `g = 10 m//s^(2)`. Length of each string AK, BK, CK and DK is equal to side length of the cube.
(a) Find tension T in string AK.
(b) Find tension `T_(0)` in string KH.
(c) Find the force (F) applied by the atmosphere on the helicopter. Assume that the atmosphere exerts a negligible force on the box.
(d) If the four strings are tied at P,Q,R and S instead of A, B, C & D, how will the quantities T, `T_(0)` and F change? Will they increase or decrease? Assume that length of the four identical strings remains same.

Answer

(a) 6467 N
(b) 22400 N
(c) 190400 N
(d) `T_(0)` and F do not change . T will increase .