A 0.100-g speck of dust is accelerated from rest to a speed of 0.900c by a constant

A 0.100-µg speck of dust is accelerated from rest to a speed of 0.900c by a constant 1.00 x 106 N force.
(a) If the non-relativistic form of Newton's second law (ΣF = mal is used, how far does the object travel to reach its final speed?
(b) Using the correct relativistic treatment of Section 37.8, how far does the object travel to reach its final speed?
(c) Which distance is greater? Why?