Source: INEP – proof and template of the 2nd day, Notebook 5 – Yellow (1st application). The ENEM Mathematics and Technologies test 2022 was administered on the 2nd day and will from question 136 to 180. This post addresses questions 151 to 165. The numbering used here is that of the Notebook 5 – Yellow; us In other notebooks the same questions appear in a different order. Template Question Subject Template 151 Graph reading and 2nd degree equation E 152 Odds: World Series C 153 Median from bar chart D 154 Proportion: game pack E 155 Linear system and maximization E 156 Proportionality and percentage C 157 Multiplicative principle B 158 Cube planning D 159 Checksum: remainder of division C 160 Scale A 161 Counting days in a tournament B 162 Odds: bingo E 163 Folding and symmetry C 164 Arithmetic mean B 165 Orthogonal projection onto the sphere E Question 151: How many times does the piston speed cancel out Statement A machine in operation has its temperature T monitored using a graphic record over time t. This machine has a piston whose speed V varies with the temperature T of the machine, according to the expression $V = T^2 - 4$. After the machine works during the time interval of 10 hours, its operator analyzes the graphic record, shown in the figure, to assess the need for possible adjustments, knowing that the machine malfunctions when the piston speed drops.