Answer:
Explanation:
This is the case of horizontal projection from a height:
Time, t = sqrt ( 2h / g )
= sqrt ( 2 * 20 / 9.8 )
= 2.02 s
Vfx = V
Vfy = g* t = 2.02 g
theta (θ)= 45 deg
tan theta (tan θ) = Vfy / Vfx
tan 45 = 2.02 g / V
V = 2.02 * 9.8
= 19.8 m/s
≅ 20m/s