The Position of a 2 $x = A \cos ( \omega t - \delta )$

Multiple Choice

The position of a 2.0-kg mass connected to a spring whose constant is 15 N/m is given by $x = A \cos ( \omega t - \delta )$ , where A = 25 cm and $\delta$ = $\delta$ /2. If the spring has a quality factor of 50 the velocity of the mass at time t = 0.50 seconds is

A) 0 m/s.
B) 0.32 m/s.
C) 0.41 m/s.
D) 0.64 m/s.