First the dart gun is fired horizontally at rest, at a height H1 =0.85 m above the ground. The trajectory of the dart is half of a parabola.
On the y axis the motion is free fall.
`H1 = (g*(t1)^2)/2` , hence `t1 =sqrt((2*H1)/g) =sqrt(2*0.85/9.81) =0.1733 s`
On the x axis the motion is uniform
`X1 = V_(1x)*t` , hence `V_(1x) =(X1)/t...
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