c
(c) Instantaneous velocity of rising mass after \( t\) sec will be \({v_t} = \sqrt {v_x^2 + v_y^2} \)

where \({v_x} = v\cos \theta = \) Horizontal component of velocity

\({v_y} = v\sin \theta - gt = \) Vertical component of velocity

\({v_t} = \sqrt {{{(v\cos \theta )}^2} + {{(v\sin \theta - gt)}^2}} \)

\({v_t} = \sqrt {{v^2} + {g^2}{t^2} - 2v\sin \theta \,gt} \)