Flat-plate solar collectors are often tilted up toward the sun in order to intercept a greater amount of direct solar radiation. The tilt angle from the horizontal also affects the rate of heat loss from the collector. Consider a 1.5-m-high and 2-m-wide solar collector that is tilted at an angle from the horizontal. The back side of the absorber is heavily insulated. The temperature of the glass cover is measured to be 40oC on a calm day when the surrounding air temperature is 20oC. Determine the rate of heat loss from the absorber plate by natural convection for = 40oC.