The correct option is D √7u ms−1
Answer is D
Since the cylinder is always in contact with wedge moving with speed 2u.
Therefore,
Vh=2u
For wedge moving with speed u, we have from wedge constraint,
uVv=tan300
Now, resultant velocity, V, of cylinder will be
V=√V2h+V2v=√(2u)2+(√3u)2
V=√7ums