2. The body of an electric motor is 360 mm in diameter and 240 mm long. It dissipates 360 W of heat and its surface temperature should not exceed 55°C. Longitudinal fins of 15 mm thickness and 40 mm height are proposed. The heat transfer coefficient is 40 W/m²-K when the ambient air is at 30°C. Determine the number of fins required, if thermal conductivity of fin material is 40 W/m-K. h=40 W/m²K 40 mm T₁ = 55°C k = 40 W/mK L-240 mm b=15 mm