A projectile thrown with an initial speed u and angle of projection 15∘ to the horizontal has a range R. If the same projectile is thrown at an angle of 45∘ to the horizontal with speed 2u, its range will be
8 R
R=u2 sin 2 θg ∴ R ∝ u2 sin 2 θR2R1=(u2u1)2(sin 2 θ2sin 2 θ1)⇒R2=R1(2uu)2(sin 90∘sin 30∘)=8 R1