(Originais Teachy 2023) - Question Easy of Physics

A motor operates according to the Carnot cycle between two thermal sources. The hot source is at a temperature of 500 K and the cold source at 300 K. Determine the efficiency of the motor, knowing that the efficiency of the Carnot cycle is calculated by the expression 1 - (Tcold/Thot), where Tcold and Thot are the temperatures of the cold and hot sources, respectively. Discuss briefly the importance of the maximum efficiency of the Carnot cycle in practical applications of thermal engines.

A student is observing an object through a converging lens with a focal length of 10 cm. The object is located 40 cm away from the lens. (Consider that the thin lens approximation is valid). Based on this information: 1) Calculate the position of the image formed by the lens. 2) Determine the size of the image relative to the size of the object, knowing that the lens obeys the Gauss equation (1/f = 1/p + 1/p'), where f is the focal distance of the lens, p is the distance from the object to the lens, and p' is the distance from the image to the lens, all measured in cm. Consider that the coordinate system used has its origin at the lens's optical center, with the main axis oriented positively to the right, and that real images have a positive sign and virtual images have a negative sign.