As shown, there is rotating spotlight at a perpendicular distance `h` from a horizontal floor. The light revolves at `N rev//min` about a horizontal axis perpendicular to the paper. Find the velocity of light spot traveling along the floor.

Explanation

At time `t, theta` is the angle between vertical line and light beam. At this time, the spot of light beam is at distance `x` from the vertical line.
`tantheta=(x)/(h)`
`x=h tantheta`
`v=(dx)/(dt)=h sec^(2)theta (d theta)/(dt)=hsec^(2)thetaomega`
`=h sec^(2)theta(2pi N)/(60)`
`v=(pi N hsec^(2)theta)/(30)`