We have,
Internal diameter of pipe = 2 cm
Internal radius of pipe = d/2 = 2/2 = 1cm
Rate of flow of water = 6 m/s = 600 cm/s
Radius of base of cylindrical tank = 60 cm
Rise in height in cylindrical tank = rate of flow of water × total time × volume of pipe / volume of cylindrical tank
= (600 × 30 × 60 × π × 1 × 1) / (π × 60 × 60)
= 1080000/3600
= 300 cm
= 3m
∴ Rise in water level is 3m.