1.A soccer goalie tries to throw a ball between the feet of an opponent. The ball is thrown from a height0.70 m at an angle of 20.0below the horizontal with an initial speed of 2.0 m/s. How long does it takefor the ball to hit the ground?(

a) 0.38 s

(b)40.31 s

(c) 0.45 s

(d) 0.63 s

(e) 0.24 sSolution: The equation of motion is

0 =h-v0sin t-12gt2Solving fortgivest=-v0sinqv20sin2+ 2ghgt=(-2 m/s) sin(20) +p(-2 m/s)2sin2(20) + 2(9.81 m/s2)(0.7 m)9.81 m/s2t= 0.3

i got the answer but why is velocity negative in the equation