v = 5t²+2t
vdt = (5t²+2t)dt
Integrating,
vt = 5t³/3 + t² + c
vt = S,
S = 5t³/3 + t² + c,
When time is zero, displacement is zero.
Therefore, 0 = 0 + 0 + c
c=0
S = 5t³/3 + t²
Put t = 2,
S = 40/3 + 4 = 52/3
Put t=1,
S= 5 /3+ 1 = 8/3
Therefore, the distance travelled in the 2nd second = 52/3-8/3 = 44/3 