Question

On a particle, moving on a circular path with a constant speed $v$ , light is thrown from a projector placed at the centre of the circular path. The shadow of the particle is formed on the wall. The velocity of shadow, up the wall, is

• A. $\text{v }{\text{sec}}^2\varphi$
• B. $\text{v }{\text{cos}}^2\varphi$
• C. $\text{v }\text{cos }\varphi$
• D. None of these

Answer 1

Answer: (A)

$\frac{{\text{v}}^{\prime }\text{ cos }\varphi }{\text{R }\text{sec }\varphi }=\frac{\text{v}}{\text{R}}$
${\text{v}}^{\prime }=\text{v }{\text{sec}}^2\varphi$