7. If the extension (x metres) of an undamped vibrating spring after a time of t seconds is given by the expression x=0.54cos(0.3t - 0.15) + 3.2 Find the speed (v) and acceleration (a) of the spring at times t=0 and t = 0.2 seconds. Note: speed (v) can be expressed as dx/dt and acceleration (a) expressed as dv/dt Full set of clear calculations