A. The truck exerts a greater force on the car than the car exerts on the truck.
The correct answer of this question: 18789.79 watt.
EXPLANATION:
As per the question, the surface area of the log is given as A = ![0.25\ m^2](https://tex.z-dn.net/?f=0.25%5C%20m%5E2)
The temperature of the of the surface of the log t = 800 ![^0C](https://tex.z-dn.net/?f=%5E0C)
We know that ![t^0C\ =(273+t)\ K](https://tex.z-dn.net/?f=t%5E0C%5C%20%3D%28273%2Bt%29%5C%20K)
⇒ 800 degree celsius= 800+273 K
= 1073 K.
Here, K stands for kelvin scale.
We are asked to calculate the thermal power radiation .
The power is defined as the amount of energy released per unit time.
Hence, power is calculated as-
Power P = ![\sigma AT^4](https://tex.z-dn.net/?f=%5Csigma%20AT%5E4)
= ![5.67\times 10^{-8} \times 0.25\times (1073)^4\ watt](https://tex.z-dn.net/?f=5.67%5Ctimes%2010%5E%7B-8%7D%20%5Ctimes%200.25%5Ctimes%20%281073%29%5E4%5C%20watt)
= 18789.79 watt. [ans]
Here,
is the Stefan-Boltzmann constant and T is the absolute temperature of the log.