A mass m attached to a spring oscillates every 2 sec. If the mass is increased by 2 kg, then time-period increases by 1 sec. The initial mass is
1.6 kg
3.9 kg
9.6 kg
12.6 kg
T=2πmk⇒T2T1=m2m1⇒32=m+2m⇒94=m+2m
⇒m=85kg=1.6 kg