Answer :
Answer:
[tex]\theta_2 \approx 40.5^{\circ}[/tex]
Explanation:
Given:
velocity of the ball first and ball second, [tex]v_1=v_2=v\,m.s^{-1}[/tex]
angle of projection of the first ball, [tex]\theta_1= 72^{\circ}[/tex]
∵The balls should land at the same point,
∴their range of projectile,
[tex]R_1=R_2=R\,m[/tex]
As we know for the range of projectile:
[tex]R=\frac{v^2}{g}.sin\,2\theta[/tex]
∵ we have equal range in both the cases
[tex]\therefore \frac{v_1^2}{g}.sin\,2\theta_1=\frac{v_2^2}{g}.sin\,2\theta_2[/tex]
[tex]\Rightarrow \frac{v^2}{g}.sin\,(2\times 72) =\frac{v^2}{g}.sin\,2\theta_2[/tex]
[tex]\Rightarrow sin 144^{\circ}=sin\,2\theta_2[/tex]
[tex]2\theta_2=sin^{-1}[sin 144^{\circ}][/tex]
[tex]\theta_2=\frac{1}{2}\times sin^{-1}[sin 144^{\circ}][/tex]
[tex]\theta_2 \approx 40.5^{\circ}[/tex]