Final answer:
The temperature of the tent canvas can be calculated using the Stefan-Boltzmann Law. Using the given values, the temperature of the tent canvas is found to be 48.5°C. If the sunlit side of the tent was white and the rider wore a white tunic, the temperature of the tent canvas would be lower due to reduced heat absorption.
Step-by-step explanation:
The temperature of the tent canvas can be calculated using the Stefan-Boltzmann Law, which relates the rate of heat transfer by radiation to the temperature and emissivity of the object. The equation is:
Rate of heat transfer = emissivity x Stefan-Boltzmann constant x surface area x (temperature of the object^4 - temperature of surroundings^4)
In this case, the rate of heat transfer is given as 20.0 W, the emissivity is 0.970, the surface area is 0.400 m², and the temperature of the surroundings and the rider's skin temperature are both 34.0°C. Plugging in these values into the equation, we can solve for the temperature of the tent canvas, which comes out to be 48.5°C.
If the sunlit side of the tent was nearly pure white and the rider was covered by a white tunic, the temperature of the tent canvas would be lower than 48.5°C. A white object reflects more radiant energy than it absorbs, so less heat would be absorbed by the tent canvas. Additionally, the white tunic would prevent the heat from transferring to the rider, further reducing the temperature of the tent canvas.