A rod can freely rotate in vertical plane about a hinge at its bottom. Two strings tie the top of the rod with blocks A and B as shown in the figure. At the instant shown, the rod is vertical and the speed of block. A is 4 m/s downwards. Then the speed of block B (in `m//s`) is

Answer

3

Explanation

`vec(A)implies2hat(i)`
`vec(B) implies5 km 37^(@)` south of east
`vec(B) = 4 hat(i)-3hat(j)`
`vec(C )implies x hat(j)`
`vec(R) = vec(A)+vec(B)+vec(C )`
`6hat(i)implies2hat(i)+4hat(i)-3hat(j)+xhat(j)`
`implies x-3 =0`
`x = 3`