A physics teacher designs a rather unusual demonstration of simple harmonic motion which utilizes a combination of a 4. 0 kg mass and two identical springs mounted on a smooth horizontal table. Each spring has a force constant of 75 n/m and an unstretched length of 0. 25 m. The motion is started by releasing the mass from point a, where both springs have lengths of 0. 5 m. One cycle is carried out as the mass moves from a to b to c to b to a. From the information given, find the speed of the mass as it passes through the central point b.