Answer
given,
mass of the steel ball = 35 g = 0.035 kg
the horizontal distance is
( v cos θ ) t = 4.8..........(1)
the vertical distance is
[tex](v sin \theta ) t - \dfrac{1}{2}gt^2 = 1.2[/tex]...(2)
since,
[tex](v sin \theta )t = 4 [/tex]
[tex]\dfrac{1}{2}gt^2 = (v sin \theta) t - 1.2[/tex]
[tex]\dfrac{1}{2}gt^2 = 4 - 1.2[/tex]..................(3)
using equation(2) and (3)
(v t)² (cos²θ+ sin²θ) = 4.8² + 4²
(v t)² = 39.04
[tex]\dfrac{1}{2}gt^2 = 4 - 1.2[/tex]
[tex]t = \sqrt{\dfrac{2(4-1.2)}{9.8}}[/tex]
t = 0.76 s
the speed is
vt = 6.25
v × 0.76 = 6.25
v = 8.22 m/s