Please solve with an explanation, thanks. Also, how do we know if we should use length or corrected length ?

a A1 m long, 5 cm outer diameter copper pipe with surface threads acting as fins carries hot oil at 110C. Each fin length is 1 mm with a thickness of 1 mm too, with a pitch (fin distance) of 1 mm. If the ambient temperature is 30C, calculate the heat transfer out of the finned area of the pipe. Use the figure for assistance. Take the convective heat transfer coefficient as 50 W/m.C. Ltube = 1 m Industrial P= 1 mm L=1 mm D = 5 cm t=1 mm