An object is thrown horizontally from the open window of a building. If the initial speed of the object is 20 m/s and it hits the ground 2.0 s later, from what height was it thrown? (Neglect air resistance and assume the ground is level.) please give process

 A Converging bundle of light rays in the shape of cone with a vertex angle of 45° falls on a circular diaphragm of 20 cm diameter. A lens with power 5D is fixed in the diaphragm. Diameter of face of lens is equal ot that of diaphragm. If the vertex angle of new cone is 0, then tane =

(A) 1.5

(B) 2

(C) 3

(D) 1