{"id":11446,"date":"2024-11-12T13:31:22","date_gmt":"2024-11-12T13:31:22","guid":{"rendered":"https:\/\/fisicaevestibular.com.br\/novo\/?page_id=11446"},"modified":"2024-12-02T17:34:34","modified_gmt":"2024-12-02T17:34:34","slug":"enem-mec-2021-en","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/enem-mec-2021-en\/","title":{"rendered":"Enem – Mec – 2021 – EN"},"content":{"rendered":"

ENEM \u2013 MEC \u2013 2021<\/span><\/h1>\n
\n

ENEM \u2013 MEC \u2013 2021<\/span><\/strong><\/p>\n

Compare this and other resolutions from ENEM 2021 and from the entrance exams of other Universities at\u00a0\u00a0<\/span>fisicaevestibular.com.br<\/span><\/a>\u00a0\u00a0with others and you will see that it:<\/span><\/strong><\/p>\n

It has a better look and more informative illustrations.<\/span><\/strong><\/p>\n

It was made for students who really have difficulties with Physics and Mathematics concepts, always trying to explain the smallest details.<\/span><\/strong><\/p>\n

It doesn’t just include formulas, always trying to show their origins and uses.<\/span><\/strong><\/p>\n

Whenever necessary, he tries to explain through drawings and illustrations.<\/span><\/strong><\/p>\n

Don’t skip steps explaining sequence by sequence.<\/span><\/strong><\/p>\n

There is a great deal of concern that the student understands the solutions. The teacher puts himself in the student’s shoes.<\/span><\/strong><\/p>\n

It often provides information beyond that needed for resolutions, but is useful in future enens.<\/span><\/strong><\/p>\n

\u00a0And much, much more.<\/span><\/strong><\/p>\n

<\/p>\n

The National High School Exam (Enem) is a test created in 1998 by the Brazilian Ministry of Education (MEC) that is used as a tool to assess the overall quality of high school education in the country. Later, the exam began to be used as an entrance exam for higher education in Brazilian public universities through SiSU (Unified Selection System).<\/span><\/strong><\/p>\n

Enem is the largest exam in Brazil, with more than 8.2 million applicants in 2016.<\/span><\/strong><\/p>\n

The Enem score can be used as access to higher education in Brazilian universities that have adopted Enem as the sole or partial form of selection.<\/span><\/strong><\/p>\n

Each university has the autonomy to adhere to the new Enem as it deems best.<\/span><\/strong><\/p>\n

Along the same lines as Prouni, the\u00a0\u00a0<\/span><\/strong>Unified Selection System<\/span><\/strong><\/a>\u00a0\u00a0(SiSU) is completely online and will allow students to choose courses and places among participating higher education institutions that will use Enem as the only form of admission.<\/span><\/strong><\/p>\n

The grade is also used by people interested in earning points for the\u00a0\u00a0<\/span><\/strong>University for All Program<\/span><\/strong><\/a>\u00a0\u00a0(Prouni).<\/span><\/strong><\/p>\n

Participation in the test serves as certification of completion of high school for people over 18 years of age.<\/span><\/strong><\/p>\n

<\/a>01- (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

A\u00a0<\/span>boy<\/span><\/strong>\u00a0needs to build a circuit that turns on three\u00a0<\/span>different colored bulbs,\u00a0<\/span>one at a time.<\/span><\/strong><\/p>\n

It has<\/span><\/strong>\u00a0the bulbs, wires, a battery and two switches as\u00a0illustrated,<\/strong>\u00a0along with its three-dot symbol. When this\u00a0switch closes AB, it opens BC and vice versa.<\/strong><\/span><\/p>\n

<\/p>\n

The\u00a0<\/span>boy made five electrical circuits<\/span><\/strong>\u00a0using the\u00a0<\/span>two switches,<\/span><\/strong>\u00a0but\u00a0<\/span>only one satisfied his need.<\/span><\/strong>\u00a0This circuit is represented by<\/span><\/strong><\/p>\n

<\/p>\n

<\/p>\n


<\/p>\n

<\/p>\n

The\u00a0connection possibilities,<\/strong>\u00a0since when\u00a0one opens and the other closes are<\/strong>\u00a0:\u00a0AB with AB; AB with BC; BC with BC and BC with AB.<\/strong><\/span><\/p>\n

In each case,<\/span>\u00a0according to the statement,\u00a0only one lamp can light up.<\/strong><\/span><\/p>\n

Analyzing each alternative<\/span><\/strong>\u00a0and remembering that the electric current<\/span>\u00a0i<\/span><\/strong>\u00a0leaves the positive pole and only passes through the lamp when the circuit is closed, with it returning to the negative pole.<\/span><\/p>\n

the)<\/span><\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

<\/strong><\/p>\n

b)<\/span><\/strong><\/p>\n

<\/strong><\/p>\n

\u00a0
W)<\/span><\/strong><\/p>\n

<\/strong><\/p>\n

d)<\/span><\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

\u00a0<\/strong><\/p>\n

and)<\/span><\/strong><\/p>\n

<\/strong><\/p>\n

The only alternative that satisfies turning on a single bulb at a time is (d)<\/span><\/strong><\/p>\n

R-D<\/span><\/strong><\/p>\n

02- (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

Consider the\u00a0<\/span>comic strip,<\/span><\/strong>\u00a0in the situation where the\u00a0<\/span>temperature of the environment is lower than the body temperature<\/span><\/strong>\u00a0of the characters.<\/span><\/p>\n

<\/p>\n

WATTERSON. B. Available at: https:\/\/novaescola.org.br. Accessed on: August 11, 2014.<\/span><\/p>\n

<\/a>The\u00a0discomfort<\/strong>\u00a0mentioned by the character in the comic strip is due to the fact that,\u00a0on humid days,<\/strong><\/span><\/p>\n

a)<\/span>\u00a0the temperature of the water vapor present in the air is high.<\/span><\/strong><\/p>\n

b)<\/span>\u00a0sweat has greater difficulty evaporating from the body.<\/span><\/strong><\/p>\n

c)<\/span>\u00a0the rate of radiation absorption by the body becomes greater.<\/span><\/strong><\/p>\n

d)<\/span>\u00a0the air becomes a poor conductor and hinders the heat release process.<\/span><\/strong><\/p>\n

e)<\/span>\u00a0water vapor present in the air condenses when it comes into contact with the skin.<\/span><\/strong><\/p>\n

The\u00a0discomfort<\/strong>\u00a0mentioned by the character in the comic strip is due to the fact that,\u00a0on humid days,<\/strong><\/span><\/p>\n

Note in the\u00a0<\/span>statement<\/span>\u00a0that the\u00a0<\/span>discomfort<\/span>\u00a0<\/strong>(thermal sensation of heat)<\/span>\u00a0mentioned by the character in the comic strip is due to the fact that it occurs on\u00a0<\/span>humid days<\/span><\/strong>\u00a0and, in the\u00a0<\/span>comic strip<\/span>\u00a0, Calvin states that\u00a0<\/span>it is hot\u00a0<\/span>with Harold responding that\u00a0<\/span>what bothers him most is the\u00a0<\/span>humidity<\/span><\/strong>\u00a0.<\/span><\/p>\n

To\u00a0<\/span>reduce<\/span>\u00a0the sensation of heat, you need to\u00a0<\/span>sweat<\/span>\u00a0so that the\u00a0<\/span>evaporation<\/span>\u00a0of sweat from the skin\u00a0<\/span>removes heat from the body, cooling it down.<\/span><\/p>\n

However, as the day is humid and<\/span>\u00a0the relative humidity is higher\u00a0<\/span>(more water vapor in the air),<\/span>\u00a0it becomes\u00a0<\/span>more difficult for the body’s sweat to evaporate<\/span><\/strong>\u00a0, providing relief from the heat and cooling the body.<\/span><\/p>\n

R-B<\/span><\/strong><\/p>\n

03- (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

In the city of\u00a0<\/span>S\u00e3o Paulo<\/span><\/strong>\u00a0,\u00a0<\/span>heat islands<\/span>\u00a0are responsible for changing the direction of the sea breeze flow that should reach the source region.<\/span><\/p>\n

But as the sea breeze<\/span>\u00a0crosses the heat island,\u00a0it now encounters a\u00a0<\/span>vertical airflow<\/span>\u00a0, which transfers to it\u00a0<\/span>thermal energy<\/span>\u00a0absorbed from the city’s hot surfaces,\u00a0<\/span>moving it to higher altitudes.<\/span><\/p>\n

This way,\u00a0<\/span>there is condensation and heavy rain in the city center,<\/span>\u00a0instead of in the\u00a0<\/span>source region.<\/span><\/p>\n

The\u00a0image<\/strong>\u00a0shows the three subsystems that exchange energy in this phenomenon.<\/span><\/p>\n

<\/p>\n

In the\u00a0<\/span>process of heavy rains<\/span>\u00a0in the center of the city of S\u00e3o Paulo,\u00a0<\/span>there are two dominant mechanisms of heat transfer:\u00a0<\/span>between the Sun and the heat island,\u00a0<\/span><\/strong>and\u00a0<\/span>between the heat island and the sea breeze.<\/span><\/strong><\/p>\n

VIVEIROS. M. Heat islands divert rain from dams. Available at: www2.feis.unesp.br.<\/span><\/p>\n

Accessed on: December 3, 2019 (adapted).<\/span><\/p>\n

These mechanisms are, respectively,<\/span><\/strong><\/p>\n

a)<\/span>\u00a0irradiation and convection.<\/span><\/strong><\/p>\n

b)<\/span>\u00a0irradiation and irradiation.<\/span><\/strong><\/p>\n

c)<\/span>\u00a0conduction and irradiation.<\/span><\/strong><\/p>\n

d)<\/span>\u00a0convection and radiation.<\/span><\/strong><\/p>\n

e)<\/span>\u00a0convection and convection<\/span><\/strong><\/p>\n

If you haven’t mastered the theory, here it is:<\/span><\/strong><\/p>\n

Thermal irradiation<\/span><\/strong><\/p>\n

<\/p>\n

Thermal convection<\/span><\/strong><\/p>\n

This is the transfer of thermal energy (heat) through moving matter due to the difference in densities of that matter.<\/span><\/strong><\/p>\n

<\/p>\n

<\/p>\n

In the case of exercise, the\u00a0<\/span>transfer of heat\u00a0<\/span>between the Sun and the heat island occurs through radiation<\/span><\/strong>\u00a0(or irradiation)<\/span>\u00a0with infrared electromagnetic waves\u00a0<\/span>(heat waves)<\/span>\u00a0emitted by the Sun passing through the vacuum and then the air and reaching the heat island (in this case, downtown S\u00e3o Paulo).<\/span><\/p>\n

<\/p>\n

The\u00a0<\/span>heat transfer\u00a0<\/span>from the heat island (center of S\u00e3o Paulo) and the sea breeze<\/span><\/strong>\u00a0occurs with the rise of hot air emitted by the heat island, through\u00a0<\/span>convection<\/span><\/strong>\u00a0reaching the air from the sea breeze,\u00a0<\/span>heating it and raising it as well.<\/span><\/p>\n

A- A<\/span><\/strong><\/p>\n

04 \u2013 (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

In his study on\u00a0<\/span>falling bodies,\u00a0<\/span>Aristotle<\/span><\/strong>\u00a0stated that if we drop light\u00a0and\u00a0heavy\u00a0<\/span>bodies<\/span>\u00a0from the\u00a0same height,\u00a0the\u00a0heavier one would reach the ground faster.<\/span><\/p>\n

This idea is supported by something that is difficult to refute, direct observation of reality based on common sense.<\/span><\/p>\n

After a physics class,\u00a0<\/span>two classmates<\/span>\u00a0were arguing about\u00a0<\/span>falling bodies,<\/span>\u00a0and one tried to convince the other that he was right:<\/span><\/p>\n

Colleague A:<\/span><\/strong>\u00a0\u201c<\/span>\u00a0A heavier body falls faster than a lighter one when dropped from the same height. I prove it by dropping a stone and a cork. The stone arrives first. There you have it! It\u2019s proven!\u201d<\/span><\/p>\n

Colleague B:<\/span><\/strong>\u00a0I don\u2019t think so! I picked up a sheet of paper and dropped it. When I crumpled it, it fell faster. How is that possible? If it was the same sheet of paper, it should have fallen the same way. There has to be another explanation!\u201d<\/span><\/p>\n

H\u00dcLSENDEGER, M, An analysis of students\u2019 conceptions about falling bodies.<\/span><\/p>\n

Brazilian Journal of Physics Teaching, No. 3, Dec. 2004 (adapted).<\/span><\/p>\n

The\u00a0<\/span>common physical aspect<\/span>\u00a0that explains the\u00a0<\/span>difference in behavior of falling bodies in this discussion<\/span>\u00a0is<\/span><\/p>\n

a)<\/span>\u00a0weight of the bodies.<\/span><\/strong><\/p>\n

b)<\/span>\u00a0air resistance.<\/span><\/strong><\/p>\n

c)<\/span>\u00a0mass of the bodies.<\/span><\/strong><\/p>\n

d)<\/span>\u00a0density of bodies.<\/span><\/strong><\/p>\n

e)<\/span>\u00a0acceleration of gravity.<\/span><\/strong><\/p>\n

Air resistance force<\/span><\/strong><\/p>\n

\u00a0\u00a0We call\u00a0<\/span>free fall\u00a0<\/span>\u00a0the fall of bodies\u00a0<\/span>\u00a0disregarding\u00a0\u00a0<\/span>air resistance. If there is air resistance\u00a0\u00a0<\/span>it will not be free fall.<\/span><\/p>\n

Disregarding the air,<\/span><\/strong>\u00a0all bodies,\u00a0<\/span>\u00a0regardless of their shape or mass, close to the\u00a0<\/span>\u00a0Earth’s surface (approximately up to 8 km high),\u00a0<\/span>\u00a0fall with the\u00a0<\/span>same acceleration (of gravity)\u00a0<\/span>\u00a0which, within that height, is approximately 9.8 m\/s\u00a0<\/span>2<\/span><\/sup>\u00a0, which we can round up to 10 m\/s\u00a0<\/span>2<\/span><\/sup>\u00a0.<\/span><\/p>\n

Example; An ant with mass m\u00a0<\/span>f<\/span><\/sub>\u00a0\u00a0and an elephant with mass M\u00a0<\/span>e<\/span><\/sub>\u00a0, in free fall, without air:<\/span><\/p>\n

<\/p>\n

Thus,\u00a0disregarding air resistance,<\/strong>\u00a0an\u00a0\u00a0elephant and an ant,\u00a0when dropped from the\u00a0same height, reach the ground at the same time.<\/span>\u00a0\u00a0\u00a0<\/p>\n

<\/p>\n

\u00a0\u00a0However, when\u00a0\u00a0<\/span>bodies move in a fluid (air or water)<\/span>\u00a0,<\/span><\/strong>\u00a0\u00a0in addition to the\u00a0\u00a0<\/span>weight, which is constant\u00a0 ,\u00a0<\/span>a force also appears\u00a0<\/span>\u00a0, contrary to the movement,\u00a0<\/span>which we call the\u00a0<\/span>air resistance force (<\/strong><\/span>\u00a0\u00a0)\u00a0<\/span>,\u00a0\u00a0<\/strong>which depends on the\u00a0\u00a0speed of the body,\u00a0its\u00a0shape and the cross-sectional area\u00a0in relation to the direction of movement in this medium, which\u00a0influences the time of fall.<\/span><\/strong>\u00a0\u00a0\u00a0<\/p>\n

R-B<\/span><\/strong><\/p>\n

05- (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

TEXT I<\/span><\/strong><\/p>\n

In\u00a0<\/span>the cordel<\/span>\u00a0entitled<\/span><\/a>Lord of the Rings,<\/span>\u00a0written by Gon\u00e7alo Ferreira da Silva, the sextet reads:<\/span><\/p>\n

The distance in relation<\/span><\/strong><\/p>\n

To our beloved planet<\/span><\/strong><\/p>\n

A little less than that of the Sun<\/span><\/strong><\/p>\n

He is distanced<\/span><\/strong><\/p>\n

And less dense than water<\/span><\/strong><\/p>\n

When in normal state<\/span><\/strong><\/p>\n

MEDEIROS. A.; AGRA. JTM, Astronomy in the literature of<\/span><\/p>\n

cordel. Physics at School, n. 1, April, 2010 (fragment).<\/span><\/p>\n

TEXT II<\/span><\/strong><\/p>\n

Average distances<\/span>\u00a0of the planets from the Sun and their\u00a0<\/span>average densities<\/span><\/p>\n

<\/p>\n

Characteristics of the planets. Available at astronco.com. Access<\/span><\/p>\n

on: 8 Nov 2019 (adapted).<\/span><\/p>\n

Considering the verses of the sextet<\/span>\u00a0and the\u00a0<\/span>information in the table,<\/span>\u00a0which\u00a0<\/span>planet<\/span><\/strong>\u00a0does the cordel refer to?<\/span><\/p>\n

a)<\/span>\u00a0Mercury.<\/span><\/strong><\/p>\n

b)<\/span>\u00a0Jupiter.<\/span><\/strong><\/p>\n

c)<\/span>\u00a0Uranus.<\/span><\/strong><\/p>\n

d)<\/span>\u00a0Saturn.<\/span><\/strong><\/p>\n

e)<\/span>\u00a0Neptune.<\/span><\/strong><\/p>\n

The\u00a0statement states that this planet is less dense than water<\/strong>\u00a0in its normal state\u00a0(liquid)\u00a0whose\u00a0density is 1.0<\/strong>\u00a0and, from the table provided, you can see that the\u00a0only planet\u00a0that satisfies this condition is\u00a0Saturn\u00a0<\/strong>(0.7).<\/strong><\/span><\/p>\n

Or even, by the title\u00a0<\/span>Lord of the Rings<\/span><\/strong>\u00a0where, although Saturn is not the only planet with rings, it is<\/span><\/p>\n

<\/p>\n

which has its most prominent rings, known as\u00a0<\/span>\u201cSaturn\u2019s rings\u201d.<\/span><\/strong><\/p>\n

R-D<\/span><\/strong><\/p>\n

06- (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

Scientists<\/span><\/strong>\u00a0at the University of New South Wales in Australia demonstrated in 2012 that<\/span>\u00a0Ohm’s Law is valid even for very thin wires,<\/span>\u00a0whose cross-sectional area comprises just a few atoms. The\u00a0table<\/strong>\u00a0shows the\u00a0areas\u00a0and\u00a0lengths of some of the wires constructed\u00a0(respectively with the same units of measurement).<\/span><\/p>\n

Consider that the\u00a0<\/span>resistivity remains constant<\/span><\/strong>\u00a0for all geometries\u00a0<\/span>(an approximation confirmed by the study).<\/span><\/p>\n

<\/p>\n

WEBER. S.B, et. al Ohm’s Law Survives the Atomic Scale.<\/span><\/p>\n

Science. n. 335. Jan. 2012 (adapted).<\/span><\/p>\n

The\u00a0<\/span>electrical resistances<\/span><\/strong>\u00a0of the wires, in\u00a0<\/span>increasing order,<\/span><\/strong>\u00a0are<\/span><\/p>\n

<\/p>\n

This question in which\u00a0<\/span>resistivity appears<\/span><\/strong><\/a>refers to Ohm’s second law given below:<\/span><\/strong><\/p>\n

<\/p>\n

<\/p>\n

R-C<\/span><\/strong><\/p>\n

07- (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

Two spheres<\/span>\u00a0<\/strong>charged with<\/span>\u00a0charges of equal magnitude<\/span><\/strong>\u00a0and<\/span>\u00a0opposite signs<\/span><\/strong>\u00a0are connected by a rigid insulating rod in the shape of a dumbbell.<\/span><\/p>\n

THE<\/span><\/a>system moves<\/span><\/strong>\u00a0under the action of gravity in a region that has a<\/span>\u00a0uniform horizontal magnetic field\u00a0<\/span>\u00a0\u00a0, from left to right.<\/span><\/p>\n

The\u00a0<\/span>image\u00a0<\/span>shows<\/span><\/strong>\u00a0the system\u00a0<\/span>seen from top to bottom,<\/span>\u00a0in the same direction as the\u00a0<\/span>acceleration of gravity (\u00a0<\/span>)\u00a0<\/span><\/strong>\u00a0that acts in the region.<\/span><\/p>\n

<\/p>\n

Seen from above<\/span><\/strong>\u00a0, the<\/span>\u00a0schematic diagram of the\u00a0<\/span>magnetic forces<\/span><\/strong>\u00a0acting on the system, at the<\/span>\u00a0initial moment<\/span>\u00a0when the charges penetrate the magnetic field region,<\/span>\u00a0is represented in<\/span><\/p>\n

<\/p>\n

<\/p>\n

<\/p>\n

<\/p>\n

Since the other charge\u00a0<\/span>is negative,<\/span><\/strong>\u00a0the\u00a0<\/span>magnetic force<\/span><\/strong>\u00a0on it has the\u00a0<\/span>same direction (vertical)<\/span><\/strong>\u00a0but\u00a0<\/span>opposite to that of the positive charge (upwards).<\/span><\/strong><\/p>\n

A- A<\/span><\/strong><\/p>\n

08- (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

When\u00a0<\/span>setting up a kitchen<\/span>\u00a0for a restaurant,\u00a0<\/span>choosing the correct material<\/span>\u00a0for the\u00a0<\/span>pans<\/span>\u00a0is<\/span><\/p>\n

<\/p>\n

important,<\/span>\u00a0because the pan that\u00a0<\/span>conducts more heat is able to cook food more quickly<\/span><\/strong>\u00a0and, therefore,\u00a0<\/span>there is a saving of gas<\/span>\u00a0.<\/span><\/p>\n

<\/p>\n

<\/p>\n

<\/a>The\u00a0<\/span>ascending order from most economical to least economical<\/span><\/strong>\u00a0is<\/span><\/p>\n

a)<\/span>\u00a0copper-steel, aluminum and iron.<\/span><\/strong><\/p>\n

b)<\/span>\u00a0aluminum, copper-steel and iron.<\/span><\/strong><\/p>\n

c)<\/span>\u00a0copper-steel, iron and aluminum.<\/span><\/strong><\/p>\n

d)<\/span>\u00a0aluminum, iron and copper-steel.<\/span><\/strong><\/p>\n

e)<\/span>\u00a0iron, aluminum and copper-steel.<\/span><\/strong><\/p>\n

According to the statement,<\/span><\/strong>\u00a0the pan that<\/span>\u00a0conducts more heat is able to cook food more quickly<\/span><\/strong>\u00a0and, therefore,<\/span>\u00a0there is a saving of gas.<\/span><\/p>\n

<\/p>\n

<\/p>\n

<\/a>R-B<\/span><\/strong><\/p>\n

09- (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

An\u00a0<\/span>electrocardiogram<\/span>\u00a0<\/strong>is a\u00a0<\/span>cardiac exam<\/span>\u00a0that measures the intensity of electrical signals coming from the heart.<\/span><\/p>\n

The\u00a0<\/span>image<\/span>\u00a0<\/strong>shows the typical result obtained in a healthy patient and the\u00a0<\/span>signal intensity (VEC) as a function of time.<\/span><\/p>\n

<\/p>\n

According to the\u00a0<\/span>electrocardiogram presented,<\/span><\/strong>\u00a0what was the<\/span><\/a>number of heartbeats per minute of this patient during the exam?<\/span><\/strong><\/p>\n

a)<\/span>\u00a030<\/span><\/strong><\/p>\n

b)<\/span>\u00a060<\/span><\/strong><\/p>\n

c)<\/span>\u00a0100<\/span><\/strong><\/p>\n

d)<\/span>\u00a0120<\/span><\/strong><\/p>\n

e)<\/span>\u00a0180<\/span><\/strong><\/p>\n

It is a\u00a0<\/span>wave phenomenon<\/span><\/strong>\u00a0based on the\u00a0<\/span>definitions of period (T) and frequency (f)<\/span><\/strong>\u00a0whose\u00a0<\/span>theory is as follows:<\/span><\/strong><\/p>\n

<\/p>\n

\u00a0\u00a0<\/p>\n

In the\u00a0<\/span>case of exercise,<\/span><\/strong>\u00a0on an electrocardiogram the\u00a0<\/span>time interval between each peak corresponds to the<\/span><\/strong><\/p>\n

period (T) of a beat<\/span><\/strong>\u00a0that is<\/span>\u00a0provided by the graph.<\/span><\/strong><\/p>\n

<\/p>\n

<\/p>\n

R-B<\/span><\/strong><\/p>\n

10- (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

Analyzing<\/span><\/strong>\u00a0the technical specifications of a<\/span>\u00a0popular car ,\u00a0<\/span>some characteristics<\/span>\u00a0can be seenin relation to its<\/span>\u00a0performance.<\/span><\/p>\n

Considering the\u00a0<\/span>same car<\/span><\/strong>\u00a0in two versions,\u00a0<\/span>one of them running on alcohol<\/span>\u00a0and the other\u00a0<\/span>,<\/span><\/p>\n

gasoline,<\/span>\u00a0you have the\u00a0<\/span>data presented in the table,<\/span>\u00a0in relation to the\u00a0<\/span>performance of each engine.<\/span><\/strong><\/p>\n

<\/strong><\/p>\n

Considering\u00a0<\/span>air resistance to be negligible,\u00a0<\/span><\/strong>which version has the greatest power?<\/strong><\/span><\/p>\n

a)<\/span>\u00a0As the gasoline version achieves the greatest acceleration, it is the one that develops the greatest power.<\/span><\/strong><\/p>\n

b)<\/span>\u00a0As the gasoline version reaches the highest kinetic energy value, it is the one that develops the greatest power.<\/span><\/strong><\/p>\n

c)<\/span>\u00a0As the alcohol version has the highest rate of variation in kinetic energy, it is the one that develops the greatest power.<\/span><\/strong><\/p>\n

d)<\/span>\u00a0As both versions present the same speed variation in the acceleration calculation, the power developed is the same.<\/span><\/strong><\/p>\n

e)<\/span>\u00a0As the gasoline version keeps the engine working for longer to reach 100 km\/h, this is the one that develops the greatest power.<\/span><\/strong><\/p>\n

The theory used to solve the exercise is as follows:<\/span><\/strong><\/p>\n

Kinetic energy theorem<\/span><\/strong><\/p>\n

In the figure below,\u00a0<\/span>the car with mass m\u00a0<\/span>\u00a0has the intensity of its\u00a0<\/span>\u00a0speed varying from Vo to V,\u00a0<\/span>\u00a0in a time interval \u2206t:<\/span><\/strong><\/p>\n

<\/p>\n

Definition of the Kinetic Energy Theorem:\u00a0<\/span>\u201cThe\u00a0<\/span>\u00a0work of the resultant\u00a0\u00a0<\/span>of\u00a0<\/span>\u00a0all\u00a0\u00a0<\/span>the forces acting on a body\u00a0<\/span>\u00a0is equal to the variation of the kinetic energy suffered by the body\u201d<\/span><\/strong><\/p>\n

Thus, the\u00a0<\/span>\u00a0work of the resulting force\u00a0<\/span>\u00a0on the car of\u00a0<\/span>\u00a0mass m\u00a0<\/span>\u00a0in the figure above in its\u00a0<\/span>\u00a0displacement\u00a0<\/span>\u00a0from\u00a0<\/span>\u00a0A to B\u00a0<\/span>\u00a0is given by:<\/span><\/strong><\/p>\n

<\/p>\n

The above expressions\u00a0<\/span>are valid whether the resulting force is conservative or not.<\/span><\/strong><\/p>\n

Power (P)<\/span><\/strong><\/p>\n

<\/p>\n

<\/p>\n

R-C<\/span><\/strong><\/p>\n

11- (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

It is possible<\/span><\/strong>\u00a0to power low-current electrical devices using<\/span>\u00a0common laboratory materials instead of traditional batteries.<\/span><\/p>\n

The\u00a0<\/span>illustration<\/span>\u00a0<\/strong>shows an assembly that\u00a0<\/span>operates a digital stopwatch.<\/span><\/p>\n

<\/p>\n

Using the\u00a0<\/span>representation of electrical projects<\/span>\u00a0, the\u00a0equivalent circuit<\/strong>\u00a0to this system is<\/span><\/p>\n

<\/p>\n

Theory \u2013 A little chemistry<\/span><\/strong><\/p>\n

Daniell stack<\/span><\/strong><\/p>\n

The\u00a0<\/span>Daniell cell<\/span>\u00a0is made up of\u00a0<\/span>two electrodes:<\/span>\u00a0the\u00a0<\/span>anode\u00a0<\/span>(negative pole)<\/span>\u00a0,<\/span><\/strong>\u00a0where zinc loses electrons, oxidizing; and the\u00a0<\/span>cathode\u00a0<\/span>(positive pole),<\/span><\/strong>\u00a0where copper cations receive electrons and are reduced.<\/span><\/p>\n

See the diagram below:<\/span><\/strong><\/p>\n

<\/p>\n

In the case of exercise:<\/span><\/strong><\/p>\n

Symbols:<\/span><\/strong><\/p>\n

<\/p>\n

There are\u00a0<\/span>two batteries<\/span><\/strong>\u00a0correctly connected<\/span>\u00a0in\u00a0<\/span>series\u00a0<\/span>(positive on one and negative on the other<\/span><\/strong>\u00a0).<\/span><\/p>\n

The\u00a0<\/span>connecting wire\u00a0<\/span><\/strong>(red)<\/strong>\u00a0comes out of the\u00a0negative pole of the battery on the right\u00a0and is connected to the\u00a0timer\u00a0(resistance device R)\u00a0from where another wire comes out connecting it to the\u00a0positive\u00a0pole of the other battery\u00a0(red wire).<\/strong><\/span><\/p>\n

<\/p>\n

Now notice that,\u00a0<\/span>coming out of the positive pole of the first battery,\u00a0<\/span>the voltmeter associated with the negative pole of the second battery<\/span>\u00a0is connected.<\/span>
Both the\u00a0<\/span>voltmeter<\/span>\u00a0and the\u00a0<\/span>stopwatch<\/span>\u00a0are\u00a0<\/span>connected in parallel to the voltage source\u00a0<\/span>(two batteries).<\/span><\/p>\n

R-B<\/span><\/strong><\/p>\n

12- (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

The\u00a0figure<\/strong>\u00a0was taken from an old\u00a0computer game\u00a0called Bang! Bang!<\/span><\/p>\n

<\/p>\n

In the game<\/span><\/strong>\u00a0,\u00a0<\/span>two competitors<\/span><\/strong>\u00a0control<\/span>\u00a0cannons A and B<\/span>\u00a0, firing bullets<\/span>\u00a0alternately<\/span>\u00a0with the aim of hitting the opponent’s cannon; to do this,<\/span>\u00a0they assign estimated values<\/span>\u00a0\u200b\u200bfor the<\/span>\u00a0module of the initial<\/span>\u00a0firing<\/span>\u00a0\u00a0\u00a0and for the<\/span>\u00a0firing angle\u00a0<\/span>(\u03b8).<\/span><\/strong><\/p>\n

At\u00a0<\/span>a certain point in a match,<\/span>\u00a0competitor\u00a0B<\/strong>\u00a0must fire;\u00a0he knows that the bullet fired previously,\u00a0\u03b8 = 53\u00b0,<\/strong>\u00a0passed\u00a0tangent to point P.<\/strong><\/span><\/p>\n

<\/p>\n

Available at: http:\/\/mebdownloads.butzke.net.br.<\/span><\/strong><\/p>\n

Accessed on: April 18, 2015 (adapted).<\/span><\/strong><\/p>\n

Based on the\u00a0<\/span>given distances<\/span><\/strong>\u00a0and maintaining the\u00a0<\/span>last firing angle,<\/span><\/strong>\u00a0what should be,\u00a0<\/span>approximately, the smallest value of\u00a0\u00a0<\/span>\u00a0that would allow the shot fired by gun B to hit gun A?<\/span><\/strong><\/p>\n

a)<\/span>\u00a030 m\/s.<\/span><\/strong><\/p>\n

b)<\/span>\u00a035 m\/s.<\/span><\/strong><\/p>\n

c)<\/span>\u00a040 m\/s.<\/span><\/strong><\/p>\n

d)<\/span>\u00a045 m\/s.<\/span><\/strong><\/p>\n

e)<\/span>\u00a050 m\/s.<\/span><\/strong><\/p>\n

This is an oblique launch whose theoretical summary is presented below:<\/span><\/strong><\/p>\n

OBLIQUE LAUNCH<\/span><\/strong><\/p>\n

Decomposition of oblique movement<\/span><\/strong><\/p>\n

The\u00a0\u00a0<\/span>oblique movement\u00a0<\/span>\u00a0is\u00a0\u00a0<\/span>decomposed<\/span>\u00a0\u00a0into a movement along the\u00a0\u00a0<\/span>horizontal direction (X axis) and another along the vertical direction (Y axis).<\/span><\/strong><\/p>\n

<\/p>\n

<\/p>\n

Equations of motion in the vertical direction<\/span><\/strong><\/p>\n

Partial movement in the horizontal direction (X axis)<\/span><\/strong><\/p>\n

<\/p>\n

<\/p>\n

<\/strong><\/p>\n

<\/strong><\/p>\n

(<\/span><\/strong><\/p>\n

<\/p>\n

R-C<\/span><\/strong><\/p>\n

13- (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

The\u00a0<\/span>wind chime<\/span><\/strong>\u00a0is made up of several metal bars of<\/span><\/a>same material and thickness,<\/span><\/strong>\u00a0but\u00a0<\/span>different lengths,\u00a0<\/span><\/strong>as shown in the figure.<\/span><\/strong><\/p>\n

<\/strong><\/p>\n

<\/strong><\/p>\n

The wind chime can be made up of open tubes or closed tubes.<\/span><\/strong><\/p>\n

Wavelengths and frequencies for a tube closed at one end<\/span><\/strong><\/p>\n

<\/p>\n

Wavelengths and frequencies for a tube open at both ends<\/span><\/strong><\/p>\n

<\/p>\n

<\/p>\n

R-D<\/span><\/strong><\/p>\n

14- (ENEM \u2013 MEC \u2013 021)<\/span><\/strong><\/p>\n

<\/p>\n

A\u00a061-year-old\u00a0<\/span>amateur cyclist<\/span><\/strong>\u00a0used a heart rate monitor to measure his heart rate<\/span>\u00a0on\u00a0<\/span>four different types of sections of the course.<\/span><\/strong><\/p>\n

The results of the maximum<\/span><\/strong>\u00a0heart rates\u00a0achieved in these sections were:<\/span><\/p>\n

\"enem\"<\/p>\n

It is known that the ideal\u00a0aerobic range<\/strong>\u00a0for gaining physical fitness is\u00a0between\u00a065% and 85%<\/strong>\u00a0of the maximum heart rate\u00a0(F\u00a0<\/strong>c max<\/sub><\/strong>\u00a0)\u00a0<\/strong>,<\/sub><\/strong>\u00a0which, in turn, is determined by\u00a0the formula:<\/span><\/p>\n

F\u00a0<\/span>c max.<\/span><\/sub>\u00a0= 220 \u2013 age,<\/span><\/strong>\u00a0where<\/span>\u00a0age<\/span>\u00a0is given in\u00a0<\/span>years<\/span><\/strong>\u00a0and<\/span>\u00a0F\u00a0<\/span>c max.<\/span><\/sub><\/strong>\u00a0is given in<\/span>\u00a0bpm\u00a0<\/span><\/strong>(beats per minute)<\/strong>\u00a0.<\/span><\/p>\n

The\u00a0<\/span>sections of the route<\/span>\u00a0in which this cyclist remains\u00a0<\/span>within his ideal aerobic range,<\/span>\u00a0for gaining physical fitness, are\u00a0<\/span><\/p>\n

a)<\/span>\u00a0light on the flat, strong on the flat, moderate climb and strong climb.<\/span><\/strong><\/p>\n

b)<\/span>\u00a0light on the flat, strong on the flat and moderate climb.<\/span><\/strong><\/p>\n

c)<\/span>\u00a0strong on the flat, moderate climb and strong climb.<\/span><\/strong><\/p>\n

d)<\/span>\u00a0strong on the flat and moderate climb.<\/span><\/strong><\/p>\n

e)<\/span>\u00a0light on the flat and steep climb.<\/span><\/strong><\/p>\n

<\/strong><\/p>\n

R-D<\/span><\/strong><\/p>\n

Click here to see more about the topic!<\/span><\/a><\/p>\n

Check out the video classes!<\/span><\/a><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

ENEM \u2013 MEC \u2013 2021 ENEM \u2013 MEC \u2013 2021 Compare this and other resolutions from ENEM 2021 and from the entrance exams of other Universities at\u00a0\u00a0fisicaevestibular.com.br\u00a0\u00a0with others and you will see that it: It has a better look and more informative illustrations. It was made for students who really have difficulties with Physics and Mathematics concepts, always trying to<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"class_list":["post-11446","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/11446","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/comments?post=11446"}],"version-history":[{"count":1,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/11446\/revisions"}],"predecessor-version":[{"id":11474,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/11446\/revisions\/11474"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=11446"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}