Question

A projectile is thrown with a speed $v$ at an angle $\theta$ with the vertical. Its average velocity between the instants it crosses half the maximum height is:

• A. $v\sin \theta$, horizontal and in the plane of projection
• B. $v\cos \theta$, horizontal and in the plane of projection
• C. $2v\sin \theta$, horizontal and perpendicular to the plane of projection
• D. $2v\cos \theta$, vertical and in the plane of projection

Answer 1

The correct option is B $v\cos \theta$, horizontal and in the plane of projection

At point $P$ and $Q$ velocity vector is average velocity of point $P$ and $Q$ is

$V_{av}=\frac{V_P+V_Q}{V_Q}=\frac{V^{1}sin\alpha \hat{j}+V\cos \theta \hat{i}+V^{1}sin\alpha \widehat{(-j)+}V\cos \theta \hat{i}}{2}=\frac{2V\cos \theta \hat{i}}{2}=V\cos \theta \hat{i}$