A very light ideal spring with a spring constant (force constant) of 250 N/m pulls horizontally on an 18-kg box that is resting on a horizontal floor. The coefficient of static
friction between the box and the floor is 0.65, and the coefficient of kinetic friction is
0.45. (HINT: Draw free-body diagram with Fs as the force applied)
(a) Draw a free-body diagram of the box labeling all forces acting on it (5 pts)
(b) How long is the spring just as the box is ready to move? (5 pts)
(c) If the spring pulls the box along with a constant forward velocity of 1.75 m/s, how long is the spring? (5 pts)