Metal balls of diameter 5 mm are heated to a temperature of 1073 K and quenched in a bath at 323 K. If density is 8000 kg/m3, specific heat = 450 J/kgK and K = 60 W/mK, then the time taken to reach 373 K is ______ (h = 1000 W/m2K)
1
ln(14)
2
3 ln(15)
3
14 ln(3)
4
ln (3)