A block of mass 100 kg is attached to the back of a truck with the help of a spring. The frictional coefficient between the truck and the block is 0.2 (take μs=μk). Acceleration of the truck is 5 m/s2 and the spring elongates by a distance of 1 cm. If the block is just about to slip, what is the force constant of the spring? Take g=10 m/s2.