A bulb is placed at the centre of a circular track of radius 10 m. A vertical wall is erected touching the track at a point P. A man is running along the track with a speed of 10 m/sec. Starting from P the speed with which his shadow is running along the wall when he is at an angular distance of 60° from P is 23. (A) 30 m/sec (B) 40 m/sec (C) 60 m/sec (D) 80 m/sec

A bulb is placed at the centre of a circular track of radius 10 m. A vertical wall is erected touching the track at a point P. A man is running along the track with a speed of 10 m/sec. Starting from P the speed with which his shadow is running along the wall when he is at an angular distance of 60° from P is 23. (A) 30 m/sec (B) 40 m/sec (C) 60 m/sec (D) 80 m/sec