A frictionless spring with a 5-kg mass can be held stretched 0.8 meters beyond its natural length by a force of 50 newtons. If the spring begins at its equilibrium position, but a push gives it an initial velocity of 2 m/sec, find the position of the mass after t seconds.
a) x(t)= 0.8 cos (7t) +27 sin (7t)
b) x(t)= 0.8 sin (7t) +2 cos (7t)
c) x(t)= 0.8 cos (7t) -2 sin (7t)
d) x(t)= 0.8 sin (7t) -2 cos (7t)
