question 1
(UFF - RJ) To determine at what height H a point light source is off the ground, flat and horizontal, the following experiment was carried out. A 0.10 m pencil was placed perpendicularly on the floor in two different positions: first in P and then in Q. Position P is exactly in the vertical that passes through the source and, in this position, there is no shadow formation of the pencil, as schematically illustrated in the figure.
In the Q position, the pencil shadow has a length 49 (forty-nine) times smaller than the distance between P and Q. Height H is approximately equal to:
a) 0.49 m
b) 1.0 m
c) 1.5 m
d) 3.0 m
e) 5.0 m
question 2
(FMTM - MG) Brazil was able to witness, during the passage from 15th to 16th of May, another total eclipse of the Moon, a fact commented on by all the newspapers. Note the headline:
Clear sky enhances eclipse show
In astronomical terms, the eclipse began at 22:05, when the satellite began to enter the twilight zone caused by blocking part of the Sun's rays. At this stage, the phenomenon is not noticed and there is practically no difference in the moon's brightness. The eclipse itself began at 23:03, when the Moon was obscured by the Earth's umbra (total shadow). In this phase – which lasted until 2:17 am – the satellite acquired a reddish hue due to the deflection of part of the light rays passing through the Earth's atmosphere.
(The State of S. Paul, 05.16.2003, adapted)
In the phenomenon observed at approximately 12:12 am, in an analogy with a room where the only light source is a lamp attached to the ceiling, it is correct to associate the sun with the lamp in the figure:
a) 2, the table to the planet Earth and one of the points C to the Moon.
b) 2, the table to planet Earth and point E to the Moon.
c) 2, one of the points D to the planet Earth and the table to the Moon.
d) 1, one of the points A to planet Earth and the table to the Moon.
e) 1, the table to planet Earth and point B to the Moon.
More questionsLooking forward to the release of the new film in the Batman franchise directed by Matt Reeves and starring Robert Pattinson, let's talk a little bit about the dark man-bat? Let's do an ethical analysis of this great DC Comics hero to understand how we can understand Batman's power through philosophy.
When two letters are able to represent the same phoneme, some doubts arise as to the correct spelling of some words. This is the case of the consonant “X” and the digraph “CH”. After all, when to use them? In this video lesson, we will present some general rules about these letters.
