PLEASE I NEED HELP WITH QUESTION ASAP!!!

A toy submarine of mass m = 0.930 kg moves around a submerged circular track of radius R = 2.07 In. The submarine's engine provides a constant propulsion force of F = 4.88 N. When the sub is in motion, it is subject to a viscous drag force exerted by the water. This force is proportional to the sub's speed: the proportionality factor is C = 1.26 kgls. Assuming it starts from rest at r = 0 s, the speed L503) of the submarine at a later time t is given by \"(a = %(1 _ e-Ch'm) where e is the base of the natural logarithm. How much time has passed when the submarines speed reaches 61% of its terminal value? What is the magnitude of the submarine's acceieration a at this time