Question

A ball is projected from top of the table with initial speed $u$ at an angle of inclination $\theta$, motion of image of ball w.r.t. ball

• A. Must be projectile
• B. Must be straight line and vertical
• C. Must be straight line and horizontal
• D. May be straight line, depends upon value of $\theta$

Answer 1

The correct option is C Must be straight line and horizontal

$\begin{array}{c}\text{Velocity of image}\text{w.r.t. object}={\overrightarrow{v}}_I-{\overrightarrow{v}}_0\\ =(-4\cos \theta \hat{ı}+u\sin \theta \hat{ȷ})-(u\cos \theta \hat{ı}+u\sin \theta \hat{ȷ})\\ {\overrightarrow{V}}_{IO}=-2u\cos \theta \hat{ı}\\ \hat{i}\text{cap means horizontally and in a straight line}\end{array}$