A section of fixed smooth circular track of radius `R` in vertical plane is shown in the figure. A block is released from position `A` and leaves the track at `B` The radius of curvature of its trajectory just after it leaves the track `B` is ?

Options

A. R
B. R/4
C. R/2
D. none of these

Answer

B

Explanation

`w_(g)=mgR(cos37^(@)-cos53^(@))=1/2 mv^(2)`
`rArr v^(2) =(2gR)/5`
`R_(c)=(v^(2))/(a_(N))=(v^(2))/(g cos 37^(@)) =(2gR//5)/(4g//5) =R/2`