A block of 200 g mass moves with a uniform speed in a horizontal circular groove, with vertical side walls of radius 20 cm. If the block takes 40 s to complete one round, the normal force by the side walls of the groove is :

Options

A. `0.0314 N `
B. `6.28 xx 10 ^(-3) N`
C. `9.859 xx 10^(-2) N`
D. `9.859 xx 10 ^(-4) N`