def calculate_velocity(c, t):
    """
    Calculates a velocity given a set of quintic coefficients and a time.

    Args
        c: List of coefficients generated by a quintic polynomial 
            trajectory generator.
        t: Time at which to calculate the velocity

    Returns
        Velocity
    """
    return 5 * c[0] * t**4 + 4 * c[1] * t**3 + 3 * c[2] * t**2 + 2 * c[3] * t + c[4]