(Originais Teachy 2023) - Question Medium of Physics

Beverages can be chilled more quickly using styrofoam boxes containing ice and a little commercial coarse salt. In this process, the ice melts with consequent formation of liquid and cooling of the beverages. An erroneous interpretation, based on common sense, relates this effect to the great ability of coarse salt to remove heat from the ice. From a scientific point of view, rapid cooling occurs due to more efficient heat transfer between the ice, salt, and beverages.

Your image O' and five observers: 1, 2, 3, 4, 5. Which alternative presents only the observers who see the object reflected in the mirror?

In an experiment conducted in the Physics Laboratory, a group of students found that a wooden block floated in water with half of its volume submerged. Next, the same block was placed in oil where they found that it floated with $$\frac{1}{4}$$ of its volume emerged. From this information, we can affirm that the specific mass of the oil is:

The city of Salvador, famous for its hills and elevators, is a perfect example to demonstrate the force of traction. The Lacerda Elevator, one of the main postcards of the city, transports thousands of people daily between the Upper Town and the Lower Town. Suppose one day, a group of 15 people with an average mass of 70kg decide to use the elevator at the same time. Considering the elevator's mass as 500kg and the acceleration due to gravity equal to 10 m/s², what would be the traction force on the elevator cable when it is at rest or moving at a constant speed?