Because of the periodic properties of shm, the mathematical equations that describe this motion involve sine and cosine functions. for example, if the block is released at a distance afrom its equilibrium position, its displacement x varies with time t according to the equationx=acos? t, where ? is a constant characteristic of the system. if time is measured is seconds, ? must be expressed in radians per second so that the quantity ? t is expressed in radians. use this equation and the information you now have on the acceleration and speed of the block as it moves back and forth from one side of its equilibrium position to the other to determine the correct set of equations for the block's x components of velocity and acceleration, vx and ax, respectively. in the expressions below, b and c are nonzero positive constants. because of the periodic properties of shm, the mathematical equations that describe this motion involve sine and cosine functions. for example, if the block is released at a distance from its equilibrium position, its displacement varies with time according to the equation