A small block of mass m slides on a horizontal frictionless surface as it travels around the inside of a hoop of radius R. The coefficient of friction between the block and the wall is mu; therefore, the speed v of the block decreases. In terms of m, R. Mu, and v, find expressions for each of the following. B. The block's tangential acceleration dv/dt c. The time required to reduce the speed of the block from an initial value v0 to vo/3