First slide
Projection Under uniform Acceleration
Question

A stone is thrown horizontally with velocity g ms-1 from the top of a tower of height g metre. The velocity with which it hits the ground is (in ms–1)

Moderate
Solution

Just before the stone hits the ground, its horizontal component of velocity Vx = u = 'g' and vertical component of velocity is given by 

V_y^2 = 0 + 2.g.h \Rightarrow {V_y} = \sqrt {2gh} = \sqrt {2g.g} = \sqrt 2 g

Speed with which the stone hits the ground is

V = \sqrt {V_x^2 + V_y^2} = \sqrt {{g^2} + 2{g^2}} = \sqrt 3 g

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