A 870·kg car strikes a huge spring at a speed of 16·m/s, compressing it 10.0·m. How long does it take the spring to stop the car? 2. Relevant equations - T= 2pi√m/k I don't know why I can't get this problem right. I have 2pi√870/2227.2=3.92 then you would divide that by 2 because it's half the period to get it stopped which gives me 1.96 which doesn't work.