Question

An object is projected from ground level with launch speed u and at an angle theta above the horizontal. Find the values of u and theta if the range is 28.6m and time of flight is 1.43secs.

thanks!

Answer 1

L = 28.6 m, t = 1.43 s, vₒ = ? α = ?

t =2• vₒ•sinα/g , => vₒ=g•t/2•sinα,
L =vₒ²•sin2α/g, =
(g•t/2•sinα)² •(2•sinα•cosα/g) =
= g•t²/2•tanα,
tanα = g•t²/2•L =
= 9.8•(1.43)²/2•28.6 =0.35,
α =19.3º.
vₒ=g•t/2•sinα =
= 9.8•1.43/2•sin19.3º=21.2 m/s.