Q.

A particle is moving in a circle of radius 50 cm in such a way that at any instant the normal and tangential components of its acceleration are equal. If its speed at t = 0 is 4 m/s, the time taken to complete the first revolution will be 1α[1-e-2π]s, where α= _____________ .            [2024]


Ans.

(8)     |ac|=|at|   

          v2r=dvdt4vdvv2=0tdtr

          [-1v]4v=tr-1v+14=2t

          v=41-8t=dsdt

           40tdt1-8t=0sds

          (r=0.5m s=2πr=π)

          4×[ln(1-8t)]0t-8=π

           lln(1-8t)=-2π

           1-8t=e-2πt=18(1-e-2π)

            So, α=8