A horizontal force F slide is exerted on a 9.0-kg box sliding on a polished floor. As the box moves, the magnitude of F slide increases smoothly from 0 to 5.0 N in 5.0 s.

a. What is the box's speed at t = 5.0 s if it starts from rest? Ignore any friction between the box and the floor.

b. What is the box's speed at t = 5.0 s if at t = 0 it has a velocity of 3.5 m/s in the direction opposite the direction of F slide? Ignore any friction between the box and the floor. Assume that the positive direction is the direction of F slide.